Why Jews Fast
Calendrical Fast Days in the Bible
Given the prominent place of fast days in the Jewish calendar, it may come as a surprise that biblical texts contain very few mentions of public fasts with set calendar dates.
Yom Kippur – The Day of Affliction
The Torah never explicitly describes the most famous Jewish fast day as a day of fasting! Lev 16:29-34 reads:
ויקרא טז:כט וְהָיְתָ֥ה לָכֶ֖ם לְחֻקַּ֣ת עוֹלָ֑ם בַּחֹ֣דֶשׁ הַ֠שְּׁבִיעִי בֶּֽעָשׂ֨וֹר לַחֹ֜דֶשׁ תְּעַנּ֣וּ אֶת נַפְשֹֽׁתֵיכֶ֗ם… טז:ל כִּֽי־בַיּ֥וֹם הַזֶּ֛ה יְכַפֵּ֥ר עֲלֵיכֶ֖ם לְטַהֵ֣ר אֶתְכֶ֑ם מִכֹּל֙ חַטֹּ֣אתֵיכֶ֔ם לִפְנֵ֥י יְ־הֹוָ֖ה תִּטְהָֽרוּ: טז:לא שַׁבַּ֨ת שַׁבָּת֥וֹן הִיא֙ לָכֶ֔ם וְעִנִּיתֶ֖ם אֶת ־נַפְשֹׁתֵיכֶ֑ם חֻקַּ֖ת עוֹלָֽם:
Lev 16:29 And this shall be to you a law for all time: In the seventh month, on the tenth day of the month, you shall practice self-affliction… 16:30 For on this day atonement shall be made for you to cleanse you of all your sins; you shall be clean before YHWH. 16:31 It shall be a sabbath of complete rest for you, and you shall practice self-affliction; it is a law for all time (NJPS with adjustments).
Yom Kippur is referenced two other times in the Torah, once as the day of when the Jubilee as declared (Lev 25:9), and once to describe its sacrifices (Num 29:7-11). This latter reference contains the same phrase highlighted above:
במדבר כט:ז וּבֶעָשׂוֹר֩ לַחֹ֨דֶשׁ הַשְּׁבִיעִ֜י הַזֶּ֗ה מִֽקְרָא קֹ֙דֶשׁ֙ יִהְיֶ֣ה לָכֶ֔ם וְעִנִּיתֶ֖ם אֶת נַפְשֹׁתֵיכֶ֑ם כָּל־מְלָאכָ֖ה לֹ֥א תַעֲשֽׂוּ:
Num 29:7 On the tenth day of the same seventh month you shall observe a sacred occasion when you shall practice self-affliction. You shall do no work.
The Bible contains no other references to Yom Kippur, and thus the precise practices implied by the phrase “self-affliction” remain uncertain. Second Temple tradition, rabbinic tradition, as well as Karaite and Samaritan tradition, however, all interpret the Torah’s reference to self-affliction to be a reference to fasting. That fasting is meant by, or included in affliction may be adduced by looking at other biblical verses where the term fasting and self-affliction are used in parallel, especially Isaiah 38:3:
ישעיהו נח:ג לָ֤מָּה צַּ֙מְנוּ֙ וְלֹ֣א רָאִ֔יתָ
עִנִּ֥ינוּ נַפְשֵׁ֖נוּ וְלֹ֣א תֵדָ֑ע
Isa 58:3 “Why, when we fasted, did You not see?
When we afflicted ourselves, did You pay no heed?” 
Mourning – The Four Fasts over the Destruction of Judah
The only public, calendrical fast days referenced in the Bible as such are the four days of mourning for the Temple in Zechariah:
זכריה ח:יט כֹּֽה־אָמַ֞ר יְ־הֹוָ֣ה צְבָא֗וֹת צ֣וֹם הָרְבִיעִ֡י וְצ֣וֹם הַחֲמִישִׁי֩ וְצ֨וֹם הַשְּׁבִיעִ֜י וְצ֣וֹם הָעֲשִׂירִ֗י יִהְיֶ֤ה לְבֵית יְהוּדָה֙ לְשָׂשׂ֣וֹן וּלְשִׂמְחָ֔ה וּֽלְמֹעֲדִ֖ים טוֹבִ֑ים
Zech 8:19 Thus said YHWH of Hosts: The fast of the fourth month, the fast of the fifth month, the fast of the seventh month, and the fast of the tenth month shall become occasions for joy and gladness, happy festivals for the House of Judah;
The verse seems to imply an inversion, where in the future these days will be a “happy festival,” implying that in the prophet’s time they were days of mourning.
Fasting as a Mourning Practice
Fasting in the Bible is often described or prescribed in reaction to a harsh decree; this may be supplemented by other practices that typify mourning, such as wearing sackcloth, crying, weeping, and putting ashes on one’s head.
Communal Fasting for Harsh decrees
The best-known example of this is the reaction of the Persian Jews to Haman’s decree:
אסתר ד:ג וּבְכָל מְדִינָ֣ה וּמְדִינָ֗ה מְקוֹם֙ אֲשֶׁ֨ר דְּבַר הַמֶּ֤לֶךְ וְדָתוֹ֙ מַגִּ֔יעַ אֵ֤בֶל גָּדוֹל֙ לַיְּהוּדִ֔ים וְצ֥וֹם וּבְכִ֖י וּמִסְפֵּ֑ד שַׂ֣ק וָאֵ֔פֶר יֻצַּ֖ע לָֽרַבִּֽים:
Esth 4:3 Also, in every province that the king’s command and decree reached, there was great mourning among the Jews,with fasting, weeping, and wailing, and everybody lay in sackcloth and ashes.
Daniel similarly combines fasting with sackcloth and ashes as part of his turning to God to pray for mercy for the Jews suffering through a long exile:
דניאל ט:ג וָאֶתְּנָ֣ה אֶת פָּנַ֗י אֶל־אֲדֹנָי֙ הָֽאֱלֹהִ֔ים לְבַקֵּ֥שׁ תְּפִלָּ֖ה וְתַחֲנוּנִ֑ים בְּצ֖וֹם וְשַׂ֥ק וָאֵֽפֶר: ט:ד וָֽאֶתְפַּֽלְלָ֛ה לַי־הֹוָ֥ה אֱלֹהַ֖י וָאֶתְוַדֶּ֑ה וָאֹֽמְרָ֗ה…
Dan 9:3 I turned my face to the Lord God, devoting myself to prayer and supplication, in fasting, in sackcloth and ashes. 9:4 I prayed to YHWH my God, making confession thus…
When a catastrophic pestilence of locusts strikes, causing widespread famine, and the priests are unable to bring offerings to God, the prophet, Joel, understood by most scholars to be a Second Temple book, instructs the people to fast and cry out to YHWH; he too prescribes other mourning rituals:
יואל א:יג חִגְר֨וּ וְסִפְד֜וּ הַכֹּהֲנִ֗ים
הֵילִ֙ילוּ֙ מְשָׁרְתֵ֣י מִזְבֵּ֔חַ
בֹּ֚אוּ לִ֣ינוּ בַשַּׂקִּ֔ים
כִּ֥י נִמְנַ֛ע מִבֵּ֥ית אֱלֹהֵיכֶ֖ם
אִסְפ֣וּ זְקֵנִ֗ים כֹּ֚ל יֹשְׁבֵ֣י הָאָ֔רֶץ
בֵּ֖ית יְ־הֹוָ֣ה אֱלֹהֵיכֶ֑ם
Joel 1:13 Gird yourselves and lament, O priests,
Wail, O ministers of the altar;
Come, spend the night in sackcloth,
O ministers of my God.
For withheld from the House of your God
Are offering and libation.
1:14 Solemnize a fast,
Proclaim an assembly;
Gather the elders—all the inhabitants of the land—
In the House of YHWH your God,
And cry out to YHWH.
The connection between fasting and mourning is also found in the relatively late book of First Maccabees (2nd cent. B.C.E.), which describes the reaction of Judah and his followers to the desolation of Jerusalem under Antiochus IV Epiphanes (the Chanukah story):
1 Macc 3:46 Then they gathered together and went to Mizpah, opposite Jerusalem, because Israel formerly had a place of prayer in Mizpah. 47 They fasted that day, put on sackcloth and sprinkled ashes on their heads, and tore their clothes (NRSV). 
This final example shows that mourning was not simply an expression of sadness but a public statement to God, hoping to convince God to help. Strikingly, none of these passages mentions teshuvah, repentance.
Fasting as Supplication: Changing God’s Mind
Although fasting characterized mourning, it was also used as part of a strategy to placate God or convince God to change a decree. (This aspect of fasting is especially relevant for Yom Kippur.)
Reaction to Defeat or Calamity
One frequent use of public mourning appears to have been in reaction to specific calamities:
Following the Benjaminite’s defeat of the Israelite army
שופטים כ:כו וַיַּעֲל֣וּ כָל בְּנֵי֩ יִשְׂרָאֵ֨ל וְכָל הָעָ֜ם וַיָּבֹ֣אוּ בֵֽית אֵ֗ל וַיִּבְכּוּ֙ וַיֵּ֤שְׁבוּ שָׁם֙ לִפְנֵ֣י יְ־הֹוָ֔ה וַיָּצ֥וּמוּ בַיּוֹם הַה֖וּא עַד הָעָ֑רֶב וַֽיַּעֲל֛וּ עֹל֥וֹת וּשְׁלָמִ֖ים לִפְנֵ֥י יְ־הֹוָֽה:
Judg 20:26 Then all the Israelites, all the army, went up and came to Bethel and they sat there, weeping before YHWH. They fasted that day until evening, and presented burnt offerings and offerings of well-being to YHWH.
Following the Philistine’s defeat of Israel’s army
שמואל א ז:ה וַיֹּ֣אמֶר שְׁמוּאֵ֔ל קִבְצ֥וּ אֶת כָּל־יִשְׂרָאֵ֖ל הַמִּצְפָּ֑תָה וְאֶתְפַּלֵּ֥ל בַּעַדְכֶ֖ם אֶל יְ־הֹוָֽה: ז:ו וַיִקָּבְצ֣וּ הַ֠מִּצְפָּתָה וַיִּֽשְׁאֲבוּ מַ֜יִם וַֽיִּשְׁפְּכ֣וּ׀ לִפְנֵ֣י יְ־הֹוָ֗ה וַיָּצ֙וּמוּ֙ בַּיּ֣וֹם הַה֔וּאוַיֹּ֣אמְרוּ שָׁ֔ם חָטָ֖אנוּ לַי־הֹוָ֑ה
1 Sam 7:5 Samuel said, “Assemble all Israel at Mizpah, and I will pray to YHWH for you.” 7:6 They assembled at Mizpah, and they drew water and poured it out before YHWH; they fasted that day, and there they confessed that they had sinned against YHWH…
Following God’s decree against Nineveh
יונה ג:ה וַֽיַּאֲמִ֛ינוּ אַנְשֵׁ֥י נִֽינְוֵ֖ה בֵּֽא-לֹהִ֑ים וַיִּקְרְאוּ צוֹם֙ וַיִּלְבְּשׁ֣וּ שַׂקִּ֔ים מִגְּדוֹלָ֖ם וְעַד־קְטַנָּֽם:
Jon 3:5 The people of Nineveh believed God. They proclaimed a fast, and great and small alike put on sackcloth. (Jonah)
Fasting to thwart Nebuchadnezzar: book of Judith
The Second Temple book of Judith (ca. 2nd century B.C.E.), which purports to tell the story of how Nebuchadnezzar, King of Assyria, sent his general Holofernes to attack Judah, and how the attack was thwarted by the righteous Judith, illustrates this as well. When the people learn that Holofernes will attack immanently, they proceed to set up for a defense, and break out into a massive mourning ritual replete with fasting (Judith Chapter 4):
Judith 4:9 And every man of Israel cried out to God with great fervor, and they humbled themselves with much fasting. 4:10 They and their wives and their children and their cattle and every resident alien and hired laborer and purchased slave– they all putsackcloth around their waists. 4:11 And all the Israelite men, women, and children living at Jerusalem prostrated themselves before the temple and put ashes on their heads and spread out their sackcloth before the Lord. 4:12 They even draped the altar with sackcloth and cried out in unison, praying fervently to the God of Israel not to allow their infants to be carried off and their wives to be taken as booty, and the towns they had inherited to be destroyed, and the sanctuary to be profaned and desecrated to the malicious joy of the Gentiles.4:13 The Lord heard their prayers and had regard for their distress; for the people fasted many days throughout Judea and in Jerusalem before the sanctuary of the Lord Almighty (NRSV).
The text here explicitly states that God hears their prayers because they fasted for many days.
Fasting in Preparation for a Battle
Fasting was also practiced before battle. For example, Saul forbids his troop from eating, ostensibly to arouse God’s sympathy and give him an advantage in battle (1 Sam 14).
שמואל א יד:כד וְאִֽישׁ יִשְׂרָאֵ֥ל נִגַּ֖שׂ בַּיּ֣וֹם הַה֑וּא וַיֹּאֶל֩ שָׁא֨וּל אֶת הָעָ֜ם לֵאמֹ֗ר אָר֣וּר הָ֠אִישׁ אֲשֶׁר יֹ֨אכַל לֶ֜חֶם עַד הָעֶ֗רֶב וְנִקַּמְתִּי֙ מֵאֹ֣יְבַ֔י וְלֹֽא טָעַ֥ם כָּל הָעָ֖ם לָֽחֶם:
1 Sam 14:24 The men of Israel were distressed that day. For Saul had laid an oath upon the troops: “Cursed be the man who eats any food before night falls and I take revenge on my enemies.” So none of the troops ate anything.
2 Maccabees 13:12 describes a similar practice at a later period (2nd cent. B.C.E.):
2 Macc 13:12 When they had all joined in the same petition and had implored the merciful Lord with weeping and fasting and lying prostrate for three days without ceasing, Judas exhorted them and ordered them to stand ready (NRSV).
The underlying assumption is that God will see his people’s pathetic state and come to their aid.
A Preventive Measure
Similar practices were also used to avert danger. For example, Ezra declares a public fast to convince God to protect him and his followers on a journey:
עזרא ח:כא וָאֶקְרָ֨א שָׁ֥ם צוֹם֙ עַל הַנָּהָ֣ר אַהֲוָ֔א לְהִתְעַנּ֖וֹת לִפְנֵ֣י אֱלֹהֵ֑ינוּ לְבַקֵּ֤שׁ מִמֶּ֙נּוּ֙ דֶּ֣רֶךְ יְשָׁרָ֔ה לָ֥נוּ וּלְטַפֵּ֖נוּ וּלְכָל רְכוּשֵֽׁנוּ: ח:כב כִּ֣י בֹ֗שְׁתִּי לִשְׁא֤וֹל מִן הַמֶּ֙לֶךְ֙ חַ֣יִל וּפָרָשִׁ֔ים לְעָזְרֵ֥נוּ מֵאוֹיֵ֖ב בַּדָּ֑רֶךְ כִּֽי אָמַ֨רְנוּ לַמֶּ֜לֶךְ לֵאמֹ֗ר יַד אֱלֹהֵ֤ינוּ עַל־כָּל מְבַקְשָׁיו֙ לְטוֹבָ֔ה וְעֻזּ֣וֹ וְאַפּ֔וֹ עַ֖ל כָּל עֹזְבָֽיו: ח:כג וַנָּצ֛וּמָה וַנְּבַקְשָׁ֥ה מֵאֱלֹהֵ֖ינוּ עַל זֹ֑את וַיֵּעָתֵ֖ר לָֽנוּ:
Ezra 8:21 I proclaimed a fast there by the Ahava River to afflict ourselves before our God to beseech Him for a smooth journey for us and for our children and for all our possessions; 8:22 for I was ashamed to ask the king for soldiers and horsemen to protect us against any enemy on the way, since we had told the king, “The benevolent care of our God is for all who seek Him, while His fierce anger is against all who forsake Him.” 8:23 So we fasted and besought our God for this, and He responded to our plea.
Changing God’s Mind
Isaiah 58 offers the clearest example that people in ancient Israel believed that public expressions of mourning, including fasting, could positively change God’s mind. This chapter argues against this view, stating that fasting alone, without proper ethical behavior is pointless:
ישעיהו נח:ג לָ֤מָּה צַּ֙מְנוּ֙ וְלֹ֣א רָאִ֔ית
עִנִּ֥ינוּ נַפְשֵׁ֖נוּ וְלֹ֣א תֵדָ֑ע
הֵ֣ן בְּי֤וֹם צֹֽמְכֶם֙ תִּמְצְאוּ־חֵ֔פֶץ
נח:ד הֵ֣ן לְרִ֤יב וּמַצָּה֙ תָּצ֔וּמוּ
וּלְהַכּ֖וֹת בְּאֶגְרֹ֣ף רֶ֑שַׁע
לְהַשְׁמִ֥יעַ בַּמָּר֖וֹם קוֹלְכֶֽם:
נח:ה הֲכָזֶ֗ה יִֽהְיֶה֙ צ֣וֹם אֶבְחָרֵ֔הוּ
י֛וֹם עַנּ֥וֹת אָדָ֖ם נַפְשׁ֑וֹ
הֲלָכֹ֨ף כְּאַגְמֹ֜ן רֹאשׁ֗וֹ
וְשַׂ֤ק וָאֵ֙פֶר֙ יַצִּ֔יעַ
וְי֥וֹם רָצ֖וֹן לַי־הֹוָֽה:
Isa 58:3 “Why, when we fasted, did You not see?
When we afflicted ourselves, did You pay no heed?”
Because on your fast day you see to your business
And oppress all your laborers!
58:4 Because you fast in strife and contention,
And you strike with a wicked fist!
Your fasting today is not such
As to make your voice heard on high.
58:5 Is such the fast I desire,
A day for men to starve their bodies?
Is it bowing the head like a bulrush
And lying in sackcloth and ashes?
Do you call that a fast,
A day when YHWH is favorable?
Jeremiah 14, in which God tells Jeremiah that he will reject repentance out of hand, similarly notes that fasting is ineffective:
ירמיהו יד:יא וַיֹּ֥אמֶר יְ־הֹוָ֖ה אֵלָ֑י אַל תִּתְפַּלֵּ֛ל בְּעַד הָעָ֥ם הַזֶּ֖ה לְטוֹבָֽה: יד:יב כִּ֣י יָצֻ֗מוּ אֵינֶ֤נִּי שֹׁמֵ֙עַ֙ אֶל רִנָּתָ֔ם וְכִ֧י יַעֲל֛וּ עֹלָ֥ה וּמִנְחָ֖ה אֵינֶ֣נִּי רֹצָ֑ם כִּ֗י בַּחֶ֙רֶב֙ וּבָרָעָ֣ב וּבַדֶּ֔בֶר אָנֹכִ֖י מְכַלֶּ֥ה אוֹתָֽם:
Jer 14:11 And YHWH said to me, “Do not pray for the benefit of this people. 14:12 When they fast, I will not listen to their outcry; and when they present burnt offering and meal offering, I will not accept them. I will exterminate them by war, famine, and disease.”
The negative attitude here is different than in Isaiah, since in this case the decree is irreversible and therefore, nothing helps; the Judahites cannot change God’s mind.
The negative attitude toward fasting is a minority opinion in the prophets; Joel’s attitude is much more typical:
יואל ב:יב וְגַם־עַתָּה֙ נְאֻם־יְ־הֹוָ֔ה
שֻׁ֥בוּ עָדַ֖י בְּכָל־לְבַבְכֶ֑ם
וּבְצ֥וֹם וּבִבְכִ֖י וּבְמִסְפֵּֽד:
ב:יג וְקִרְע֤וּ לְבַבְכֶם֙ וְאַל־בִּגְדֵיכֶ֔ם
וְשׁ֖וּבוּ אֶל־יְ־הֹוָ֣ה אֱלֹֽהֵיכֶ֑ם
כִּֽי־חַנּ֤וּן וְרַחוּם֙ ה֔וּא
אֶ֤רֶךְ אַפַּ֙יִם֙ וְרַב־ חֶ֔סֶד
ב:יד מִ֥י יוֹדֵ֖עַ יָשׁ֣וּב וְנִחָ֑ם
וְהִשְׁאִ֤יר אַֽחֲרָיו֙ בְּרָכָ֔ה
Joel 2:12 “Yet even now”—says YHWH—
“Turn to Me with all your hearts,
And with fasting, weeping, and lamenting.”
2:13 Rend your hearts rather than your garments,
And turn to YHWH your God.
For He is gracious and compassionate,
Slow to anger, abounding in kindness,
And renouncing punishment.
2:14 Who knows but He may turn and relent,
And leave a blessing behind
For meal offering and drink offering
To YHWH your God?
Personal Fasting to Change the Decree: King David and his Infant
Fasting and mourning to change God’s mind is not only used to avert communal disaster. For example, King David fasts after the prophet Nathan pronounces God’s the death of his newborn baby, as punishment for his sins of adultery and murder (2 Sam 12):
שמואל ב יב:טז וַיְבַקֵּ֥שׁ דָּוִ֛ד אֶת־הָאֱלֹהִ֖ים בְּעַ֣ד הַנָּ֑עַר וַיָּ֤צָם דָּוִד֙ צ֔וֹם וּבָ֥א וְלָ֖ן וְשָׁכַ֥ב אָֽרְצָה: יב:יז וַיָּקֻ֜מוּ זִקְנֵ֤י בֵיתוֹ֙ עָלָ֔יו לַהֲקִימ֖וֹ מִן־הָאָ֑רֶץ וְלֹ֣א אָבָ֔ה וְלֹֽא־בָרָ֥א אִתָּ֖ם לָֽחֶם:
2 Sam 12:16 David entreated God for the boy; David fasted, and he went in and spent the night lying on the ground. 12:17 The senior servants of his household tried to induce him to get up from the ground; but he refused, nor would he partake of food with them.
David fasts for an entire week, until the child dies:
יב:כ וַיָּקָם֩ דָּוִ֨ד מֵהָאָ֜רֶץ וַיִּרְחַ֣ץ וַיָּ֗סֶךְ וַיְחַלֵּף֙ שמלתו שִׂמְלֹתָ֔יו וַיָּבֹ֥א בֵית יְ־הֹוָ֖ה וַיִּשְׁתָּ֑חוּ וַיָּבֹא֙ אֶל בֵּית֔וֹוַיִּשְׁאַ֕ל וַיָּשִׂ֥ימוּ ל֛וֹ לֶ֖חֶם וַיֹּאכַֽל: יב:כא וַיֹּאמְר֤וּ עֲבָדָיו֙ אֵלָ֔יו מָֽה הַדָּבָ֥ר הַזֶּ֖ה אֲשֶׁ֣ר עָשִׂ֑יתָה בַּעֲב֞וּר הַיֶּ֤לֶד חַי֙צַ֣מְתָּ וַתֵּ֔בְךְּ וְכַֽאֲשֶׁר֙ מֵ֣ת הַיֶּ֔לֶד קַ֖מְתָּ וַתֹּ֥אכַל לָֽחֶם: יב:כב וַיֹּ֕אמֶר בְּעוֹד֙ הַיֶּ֣לֶד חַ֔י צַ֖מְתִּי וָֽאֶבְכֶּ֑ה כִּ֤י אָמַ֙רְתִּי֙ מִ֣י יוֹדֵ֔עַ יחנני וְחַנַּ֥נִי יְ־הֹוָ֖ה וְחַ֥י הַיָּֽלֶד: יב:כג וְעַתָּ֣ה׀ מֵ֗ת לָ֤מָּה זֶּה֙ אֲנִ֣י צָ֔ם הַאוּכַ֥ל לַהֲשִׁיב֖וֹ ע֑וֹד אֲנִי֙ הֹלֵ֣ךְ אֵלָ֔יו וְה֖וּא לֹֽא יָשׁ֥וּב אֵלָֽי:
12:20 Thereupon David rose from the ground; he bathed and anointed himself, and he changed his clothes. He went into the House of YHWH and prostrated himself. Then he went home and asked for food, which they set before him, and he ate. 12:21 His courtiers asked him, “Why have you acted in this manner? While the child was alive, you fasted and wept; but now that the child is dead, you rise and take food!” 12:22 He replied, “While the child was still alive, I fasted and wept because I thought: ‘Who knows? YHWH may have pity on me, and the child may live.’ 12:23 But now that he is dead, why should I fast? Can I bring him back again? I shall go to him, but he will never come back to me.”
In his servant’s eyes, David’s behavior is backwards, since he mourns his living son but stops upon the infant’s death. Nevertheless, David is explicit that he wasn’t mourning for mourning’s sake, but was trying to change God’s mind by fasting and crying.
The Beginnings of Piety: Late Second Temple Period Practice
None of the previous texts reflect the practice of fasting as reflecting a general practice of piety (i.e., to demonstrate a person’s righteousness), which developed in the Second Temple period.
Tobit – Fasting as an Act of Piety
In the book of Tobit,  an adventure tale usually dated by scholars to the third or second century BCE, Tobit tells his children on his deathbed that “Prayer with fasting is good, but better than both is almsgiving with righteousness” (Tobit 12:8; NRSV). Tobit’s statement that “prayer with fasting is good,” is wisdom style advice on proper living. This fasting is voluntary, individual, and an expression of piety, like the amount of charity an individual gives.
Judith: The Woman who Fasted Almost Every Day
The book of Judith offers a particularly extreme model of pious fasting.
Judith 8:4 Judith remained as a widow for three years and four months 8:5 at home where she set up a tent for herself on the roof of her house. She put sackcloth around her waist and dressed in widow’s clothing. 8:6 She fasted all the days of her widowhood, except the day before the sabbath and the sabbath itself, the day before the new moon and the day of the new moon, and the festivals and days of rejoicing of the house of Israel (NRSV).
Judith’s fasting is voluntary, and expresses her extreme personal piety.
Gospel of Matthew: Debating the Merits of Fasting
The Gospel of Matthew in the New Testament offers another attestation to growth of the “pious fasting” movement. In Matthew 9:14-15, Jesus debates the merits of fasting with the disciples of John the Baptist:
Matthew 9:14 Then the disciples of John came to him, saying, ‘Why do we and the Pharisees fast often, but your disciples do not fast?’ 9:15 And Jesus said to them, ‘The wedding-guests cannot mourn as long as the bridegroom is with them, can they? The days will come when the bridegroom is taken away from them, and then they will fast.’ (NRSV)
This passage implies that the disciples of John and the Pharisees fast often. The word “often” suggests that these fasts are not tied to calendrical dates or past events, but are (spontaneous or regular) acts of piety. John’s disciples want to know why Jesus’s disciples do not display similar acts of piety.
Jesus’ answer presumes that fasting is an act of mourning rather than piety. He predicts that one day, his disciples will lose their beloved—this is a reference to his own imminent death at the hands of the Romans—and when that happens, Jesus’s disciples will have reason to fast. Their fasting will function as acts of mourning, not of piety.
Reading this passage together with Jesus’ statement about fasting in the Sermon on the Mount is especially telling (Matthew 6):
Matthew 6:16 And whenever you fast, do not look dismal, like the hypocrites, for they disfigure their faces so as to show others that they are fasting. Truly I tell you, they have received their reward. 6:17 But when you fast, put oil on your head and wash your face, 6:18 so that your fasting may be seen not by others but by your Father who is in secret; and your Father who sees in secret will reward you (NRSV).
This passage suggests that Jesus, like the Pharisees and the disciples of John, believes in fasting for piety, but that such behavior should be done secretly and without fanfare. Reading these texts together suggests that Jesus’ gripe with the disciplines of John was that they made their fasting known and public, and Jesus saw this as hypocrisy. Despite this, fasting gained prominence in Christian circles and emerged as an act that reflected personal piety. In addition, many ascetic Christian communities arose that encouraged its members to avoid sex, food, and other physical indulgences that distract from leading a purely spiritual life.
A Survey of Medieval and Premodern Jewish Fasting Practices
The Mishnah and, consequently, both Talmuds have an entire tractate dedicated to fasting; its main focus is on a series of fasts that Jews of Israel are supposed to hold if rain fails to fall during the winter. This tractate also discusses a host of reasons for personal fasts, including fasts that take up only part of the day, called תענית שעות (a fast of hours).
Medieval times saw the introduction of a sixth fast day, the Fast of Esther, which is kept on the day before Purim, and a seventh, the fast of the firstborn, which is (ostensibly) kept on the day before Pesach. (We say “ostensibly” because no one actually keeps it; instead the custom has become to finish a tractate of Talmud or a seder of Mishnah called a siyyum, and have a festive meal which would exempt the firstborn male from fasting.)
Medieval sources also mention many other fast days. For hundreds of years the Ashkenazi Jewish communities kept something called ב-ה-ב, meaning 2-5-2, a reference to fasting on the second fifth and second days of the week (Monday, Thursday, Monday) after each of the three main Jewish festivals. These were instituted to repent for whatever excessive levity with which they may have behaved during the holidays. Although virtually no one fasts on these days now, many siddurim (Artscroll, Kol Peh) still have the selichot prayers for these days.
The Talmud assumes that a person will fast on the Yahrzeit of a parent. In medieval Ashkenaz, this was codified as a mitzvah. This, like the fast of the firstborn, was eventually replaced with a festive Kiddush, this time in honor of the deceased. Extremely pious individuals also fasted on righteous people’s Yahrzeits. The Shulchan Aruch even suggests that a pious person should fast every single Monday and Thursday, in remembrance of past Jewish tragedies.
A kabbalistic practice that began in medieval Ashkenaz where a man would afflict himself with fasting as well as some form of self-punishment, like self-flagellation, exposure to ice, etc. This was called תשובת המשקל, “the weighty repentance.” For example, in the Rokeach(Laws of Repentance, 6) of R. Elazar of Worms (1176-1238), the reader is told that if he wishes to perform תשובת המשקל for sexual sins, he must fast for at least 40 days, in addition to some other relatively light forms of self-affliction (no meat and wine the night before a fast, uncomfortable bed).
Fasting for Bad Dreams
Perhaps the most interesting or colorful of the personal fasts is called the תענית חלום, the fast over a (bad) dream, namely a nightmare, aimed at averting the decree that the nightmare presages. The Rabbis wax enthusiastic about this fast, saying “A fast for a nightmare works as efficaciously as fire on a piece of paper (יפה תענית לחלום כאש לנעורת).” Like the ב-ה-ב fasts described above, this relatively obscure halacha leaves its mark in the liturgy (just look in your Machzorim during the Birkat Kohanim of the high holidays).
Conclusion – Why We Fast Now
Jewish tradition offers a number of reasons for communal and personal fasting:
- Atonement (Yom Kippur, תשובת המשקל)
- Mourning (Temple fasts, Yahrzeits)
- Supplication/Prayer (rain fasts, dream fasts, fasts to avoid evil decrees)
- Piety (ב-ה-ב, random personal fasts)
Despite the robust attestation in biblical, rabbinic, and halachic literature of the benefit of fasting as a sign of mourning or repentance, most of these practices are virtually unknown in contemporary Judaism, and have been replaced with siyyums, yahrzeit kiddushes, and Tehillim groups. This gives rise to the popular perception Jews rarely fast, and that fasting in Judaism is simply something we do on fast days.
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September 21, 2015
May 25, 2021
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Dr. Rabbi Zev Farber is the Senior Editor of TheTorah.com. He holds a Ph.D. from Emory University in Jewish Religious Cultures and Hebrew Bible, an M.A. from Hebrew University in Jewish History (biblical period), as well as ordination (yoreh yoreh) and advanced ordination (yadin yadin) from Yeshivat Chovevei Torah (YCT) Rabbinical School. Zev is also a Research Fellow at the Shalom Hartman Institute's Kogod Center. He is the author of Images of Joshua in the Bible and their Reception (De Gruyter 2016) and editor (with Jacob L. Wright) of Archaeology and History of Eighth Century Judah (SBL 2018).
Dr. Malka Zeiger Simkovich is a the Crown-Ryan Chair of Jewish Studies at Catholic Theological Union in Chicago, and the director of their Catholic-Jewish Studies program. She holds a Ph.D. in Second Temple Judaism from Brandeis University, an M.A. in Hebrew Bible from Harvard University, and a B.A. in Bible Studies and Music Theory from Yeshiva University’s Stern College. In addition to her many articles, Malka is the author of The Making of Jewish Universalism: From Exile to Alexandria (2016) and Discovering Second Temple Literature: The Scriptures and Stories that Shaped Early Judaism (2018).
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