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Isaac S. D. Sassoon





Does a Day Begin in the Evening?



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Isaac S. D. Sassoon





Does a Day Begin in the Evening?






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Does a Day Begin in the Evening?

Close reading of the relevant biblical texts uncovers friction, maybe momentous historical reform.


Does a Day Begin in the Evening?

The Creation, by Lawrence W. Ladd c. 1880 Smithsonian American Art Museum

In the Festival Calendar of Leviticus 23, the final verse of the Yom Kippur paragraph insists rather emphatically that the fast shall be observed “from evening until evening.” The only parallel to this verse is Exodus 12:18 which stresses that the feast of Matzot shall be observed “from the 14th in the evening until the 21st in the evening.”

The reason these texts strike us as anomalous, is that we take it for granted that Sabbaths and festivals all run from evening to evening. Why then does the Torah spell it out just for Kippur and Matzot? As it happens, this problem exercised the Rabbis more than a little; and it will be instructive to see how they grappled with it before considering a solution proposed by scholarship.     

Yom HaKippurim – The Day of Atonement

Let us first look at Leviticus 23’s Kippur pericope closely. It consists of seven verses (26-32) in which the word ‘day’ (yom – with and without the definite article) looms large:

ויקרא כג:כז אַךְ בֶּעָשׂוֹר לַחֹדֶשׁ הַשְּׁבִיעִי הַזֶּה יוֹם הַכִּפֻּרִים הוּא… כג:כח וְכָל מְלָאכָה לֹא תַעֲשׂוּ בְּעֶצֶם הַיּוֹם הַזֶּה כִּי יוֹם כִּפֻּרִים הוּא לְכַפֵּר עֲלֵיכֶם לִפְנֵי יְ-הוָה אֱלֹהֵיכֶם. כג:כט כִּי כָל הַנֶּפֶשׁ אֲשֶׁר לֹא תְעֻנֶּה בְּעֶצֶם הַיּוֹם הַזֶּה וְנִכְרְתָה מֵעַמֶּיהָ.כג:ל וְכָל הַנֶּפֶשׁ אֲשֶׁר תַּעֲשֶׂה כָּל מְלָאכָה בְּעֶצֶם הַיּוֹם הַזֶּה
Lev 23:27 Mark, the tenth of this seventh month is the Dayof Atonement… 23:28 you shall do no work throughout that day. For it is a Day of Atonement, on which expiation is made on your behalf before YHWH your God. 23:29 Indeed, any person who does not practice self-denial throughout that day shall be cut off from his kin; 23:30 and whoever does any work throughout that day

The date is clear, the tenth of the seventh month, but what is the exact connotation of “day” which appears five times in this passage?

Two Meanings of “Day”

Modern English dictionaries, under the entry Day, typically offer the following two definitions:

  1. The time between sunrise and sunset;
  2. A duration of 24 hours corresponding to a complete revolution of the earth on its axis.

Genesis 1:5 suggests that ancient Israelites’ yom served both senses:

וַיִּקְרָא אֱלֹהִים לָאוֹר יוֹם וְלַחֹשֶׁךְ קָרָא לָיְלָה וַיְהִי עֶרֶב וַיְהִי בֹקֶר יוֹם אֶחָד.
God called the light day and the darkness He called night and there was evening and there was morning, day one.

However, the rabbis, at least overtly, betray no interest in the verse’s tantalizing paronomasia. Moreover, they ignore one of the verse’s key words, namely, boker, a noun whose scriptural meanings include morning, daybreak or, dawn. Nowhere does biblical bokerdenote a period from dawn to dusk; least of all in Gen 1 where v. 5 precludes it by declaring that the word for the daylight hours is none other than yom. But it had to wait for the Middle Ages for boker to receive its due, when R. Samuel b. Meir (Rashbam ca. 1085-1158) mooted that a straightforward construal of vayhi erev vayhi boker [it was evening and it was morning] describes a time-unit ending at dawn.

In fact so completely did the Rabbis discount boker, that they were able to elicit from the verse an opposite meaning. Thus, Gen 1:5’s “and there was evening and there was morning day one” described for them a timespan that commenced in the evening, continued on through morning, ending twenty-four hours after it started with the onset of the next nightfall.[1] Needless to say, this stereotypical phrase, which figures in the next five creation paragraphs, was understood consistently this way by the rabbis. What is more, so firmly established was this definition, that they axiomatically treated yom’s occurrence in other Torah texts as possessing the same denotation. 

Annulling Vows on the Yom They Are Heard

A case in point is yom in the text that grants a father authority to annul vows made by a daughter under his guardianship on the yom he hears about them (Num 30:6), and grants the same power to a husband to annul his wife’s vows on the yom he hears (Num 30:9,13):

במדבר ל:ו וְאִם הֵנִיא אָבִיהָ אֹתָהּ בְּיוֹם שָׁמְעוֹ…
Num 30:6 But if her father restrains her on the day he finds out…
במדבר ל:ט וְאִם בְּיוֹם שְׁמֹעַ אִישָׁהּ יָנִיא אוֹתָהּ…
Num 30:9 But if her husband restrains her on the day that he learns of it…

Without producing a proof text, the Mishnah assumes the male’s one-day veto power to run from sunset to sunset (m. Ned. 10:8).[2]

Slaughtering a Calf and Its Mother on One Yom

The same definition emerges from the Talmudic discussion of the Torah’s law against slaughtering a calf/lamb and its mother on one day:

ויקרא כב:כח וְשׁוֹר אוֹ שֶׂה אֹתוֹ וְאֶת בְּנוֹ לֹא תִשְׁחֲטוּ בְּיוֹם אֶחָד.
Lev 22:28 No animal from the herd or from the flock shall be slaughtered on the same day with its young.

The Mishnah seeks a formal definition of this verse’s “one day” (m. Hul. 5:5):

יום אחד האמור באותו ואת בנו היום הולך אחר הלילה את זו דרש שמעון בן זומא נאמר במעשה בראשית יום אחד ונאמר באותו ואת בנו יום אחד מה יום אחד האמור במעשה בראשית היום הולך אחר הלילה אף יום אחד האמור באותו ואת בנו היום הולך אחר הלילה:
Regarding the “one day” of the “it and its child” rule, day follows night. This was proven hermeneutically by Shimon ben Zoma: “In the creation story [Gen 1:5] it says ‘one day’ and regarding ‘it and its child’ it says ‘one day,’ just as in the creation story ‘one day’ means day follows night so too regarding ‘it and its child’ ‘one day’ means day follows night.”

Obviously, Shimon b. Zoma took for granted that yom x of the refrain of Genesis 1 that closes each of the six days of creation denotes a time period stretching from nightfall to nightfall.[3]Thus he is able to extrapolate from Gen 1’s “day” to Lev 23:28’s by means of a gezerah shavahanalogy. In stark contrast, the “day” of Gen 1 itself requires no elucidation; its meaning is self evident to Ben Zoma.

Indeed in a baraita juxtaposed to this Mishnah (Hul. 83a) Ben Zoma insinuates that a Torah “day” should invariably be taken to denote a time period extending from nightfall to nightfall unless indicated otherwise by Scripture. Such contrary indication appears in the Torah with respect to the cult and sacrificial meals (see further). Because the subject matter of Lev 22:28 could be [mis]understood as cult-related, a gezerah shavah[4] was called for in order to forestall the error of confusing Lev 22:28’s law with cult law. Thus, it having been demonstrated that Lev 22:28 is, as it were, the exception that proves the rule, yom’s meaning is safe. Or is it?

The Day of Atonement: The Night of the 9th?

The rabbinic understanding of yom confronts a dilemma in the final verse of the Day of Atonement pericope in Leviticus 23:

ויקרא כג:לב שַׁבַּת שַׁבָּתוֹן הוּא לָכֶם וְעִנִּיתֶם אֶת נַפְשֹׁתֵיכֶם בְּתִשְׁעָה לַחֹדֶשׁ בָּעֶרֶב מֵעֶרֶב עַד עֶרֶב תִּשְׁבְּתוּ שַׁבַּתְּכֶם.
Lev 23:32 A Sabbath of Sabbaths [or a Sabbath of rest] it is for you and you shall afflict your souls on the ninth of the month at evening from evening to evening shall you observe your Sabbath.

If yom automatically denotes a 24 hour stretch lasting from one evening until the next, this “evening to evening” stipulation would seem to be redundant. And this apparent redundancy appears to have riled the rabbis judging by the attempts – perhaps subconscious – to neutralize its inconvenient implications. By zeroing in on the “ninth,” sources such as the following divert attention from the “evening to evening” clause – which is where the menace to their definition of yom lurks.[5]

Adding Time to Yom Kippur (תוספת יום כפור)‍

The rabbis ruled that observance of Yom Kippur should begin at least a few moments before sundown. Biblical support for the ruling (referred to as “adding profane time to holy”) was delivered by R. Ishmael (b. Rosh Hashanah 9a) as follows:

נפקא ליה מדתניא: ועניתם את נפשתיכם בתשעה, יכול בתשעה? תלמוד לומר בערב – אי בערב יכול משתחשך? תלמוד לומר בתשעה. הא כיצד? מתחיל ומתענה מבעוד יום. מלמד שמוסיפין מחול על קדש. אין לי אלא בכניסתו, ביציאתו מנין? תלמוד לומר מערב עד ערב.
He [R. Ishmael] derives it from that which was taught: “You shall afflict your souls on the ninth of the month.” Could scripture actually mean [fast] on the ninth? Surely it says “at evening.” But if it says “at evening” does that not mean only with the onset of darkness? No, it says “on the ninth.” How to reconcile? One begins fasting while it is still day. This teaches that one adds from the profane onto the holy. But that applies only to its commencement, whence do we know that the same applies to its conclusion? It says, “from evening to evening.”[6]

According to R. Ishmael, then, the verse’s strange locution is there to convey the extraneous law that Yom Kippur should be extended in both directions.

Importance of Eating on the Ninth‍

As for R. Akiva, since he derives the rule about adding to the holy from an entirely different verse (Exod 34:21), the Talmud wants to know what he does with the apparently superfluous Yom Kippur verse. Answer: he learns from it the exhortation of R. Hiyya bar Rav of Difti (b. Rosh Hashanah 9a-b):

דתני חייא בר רב מדפתי: ועניתם את נפשותיכם בתשעה, וכי בתשעה מתענין? והלא בעשירי מתענין! אלא לומר לך: כל האוכל ושותה בתשיעי – מעלה עליו הכתוב כאלו התענה תשיעי ועשירי.
For Hiyya b. Rav of Difti taught: “You shall afflict your souls on the ninth” But do we really fast on the ninth? Do we not fast on the tenth?! Rather this tells you that whoever eats and drinks on the ninth, scripture reckons it for him as if he had fasted on the ninth and tenth.

In short, R. Akiva, like R. Hiyya bar Rav of Difti, extracts from this verse the mitzvah to prepare for the fast by eating a hearty meal on the ninth which is, in turn, considered as virtually on a par with fasting.

License not to Fast for Two Days in the Diaspora‍

Centuries later, the method of isolating “on the ninth” from its context yielded a third derasha. Among the rabbinic traditions challenged by the Jewish philosopher and skeptic, Uriel da Costa (d. 1640) was the observance of a second day of yom tov (festival) in the Diaspora. The practice began when rabbinic Jews relied on witnesses in Judea testifying about when they saw a new moon, in order to designate the start of a new month.

The concern was that Jews in the Diaspora would not find out which day the month began and might, consequently, observe a festival on the wrong date. Since all months in the Jewish calendar are either 29 or 30 days, the maximal margin of error is one day, so the practice became to celebrate each festival for two days, thereby covering all bases.

De Costa thought to poke a hole in the practice by pointing out that Yom Kippur was observed for a single day. Shouldn’t Diaspora Jews fast for two days just as they celebrate festivals for two days? The challenges were sent by communal leaders to the Venetian rabbi Yehudah Leon de Modena (d. 1648) for refutation. This was his riposte to de Costa’s Kippur argument.

…לא היו יכולין הצבור להתענות שני ימים [ה]יו עושים תמיד בראשון, ואף שאפשר שהיה בתשיעי, ויש קצת סמך לזה בתורה הכתוב בו ועניתם את נפשותיכם בתשעה לחרש בערב, אף שלפעמים יהיה לקצת שמכם בתשיעי יקובל.
….[T]he congregation would have been unable to fast two days, so they always fasted on the first, even if the day they fasted may have been the ninth. And there is some support for this in the Torah where it is written “you shall afflict yourselves on the ninth of the month.” Although at times some of you might observe it on the ninth, it will be acceptable.[7]

Here R. Modena takes a homiletic route, reading the verse as a concession to human frailty. Recognizing the impossibility of fasting for two consecutive days, this text is saying that Yom Kippur observance on the ninth, in cases of unavoidable calendrical error, still counts as Yom Kippur observance. This charming derasha will have served as a polemical defense at the time, but one may doubt whether Modena himself believed it to inhere, even latently, in the biblical text.

Inasmuch as they dwell on “the ninth” at the expense of “evening to evening” these three strategies fail to convince. For the verse’s dynamite is precisely its evident need to fix the fast – called yom throughout the pericope – from evening to evening. This need calls into question the rabbinic premise that a yom’s parameters are cut and dried. By and by we shall present our alternative theory, but not before reviewing a “twin” text.

Week of Matzot: Night of the 14th?

As already noted in the introduction, a comparable redundancy manifests itself in Exodus 12, where the lemma yom – in the singular and plural, with and without suffixes – abounds. The first occurrence of yom is at v. 6:

וְהָיָה לָכֶם לְמִשְׁמֶרֶת עַד אַרְבָּעָה עָשָׂר יוֹם לַחֹדֶשׁ הַזֶּה…
You shall keep it [the paschal lamb] until the fourteenth day of this month…

The demonstrative “this” refers back to the month identified at 12:2, i.e., the first month of the year. Later in the chapter, in vv. 14-17, yom is used to specify the days when leaven must be avoided, matzot eaten, and labor refrained from. Then we come to v. 18:

שמות יב:יח בָּרִאשֹׁן בְּאַרְבָּעָה עָשָׂר יוֹם לַחֹדֶשׁ בָּעֶרֶב תֹּאכְלוּ מַצֹּת עַד יוֹם הָאֶחָד וְעֶשְׂרִים לַחֹדֶשׁ בָּעָרֶב.
Exod 12:18 In the first [month], from the fourteenth day of the month at evening, you shall eat unleavened bread until the twenty-first day of the month at evening.

Eating matzot had been promulgated already at v. 15, but thanks to P’s penchant for reiteration and inclusios, this instance would hardly grab our attention. Verse 18’s initial word barishon [= in the first (month)], on the other hand, is startling, since there could be no question as to which month was intended, the month having been identified minutely in 12:2.

But the real crux is the word “ba-erev.” Why, if days always start at sundown as a matter of course, would the verse say that the festival starts on the fourteenth in the evening?

Removing Leaven on the Fourteenth‍

Again, the rabbis obviate the ostensible redundancy by investing it with a tangential halakha: biur chametz, the elimination of leaven before the festival of Matzot begins (j. Pes. 1:1 [27a]):

בראשון בד’ עשר יום לחדש בערב תאכלו מצות וגומר מה אנן קיימין אם לאכילת מצה כבר כתיב שבעת ימים מצות תאכלו… אלא אם אינו עניין לאכילת מצה תניהו עניין לביעור חמץ
“In the first [month], on the fourteenth of the month in the evening, eat matzot, etc.” (Exod 12:18) – What is its purport? If to enjoin the eating of matzah, that was already prescribed “Seven days you shall eat matzot” (Exod 12:15).… So if it does not apply to eating matzah then let it apply to the removal of leaven.

This imaginative midrash provides scriptural authority for the rabbinic ritual of searching for leaven on the evening of the fourteenth (בדיקת חמץ) as a preliminary to its removal; a ritual which, otherwise, has little biblical support. Nevertheless, it is hardly a plain reading of the verse.

Redactions Reflecting Reform?‍

Not a few scholars believe that P’s day originally began at daybreak. The stubborn boker of Gen 1 constitutes pretty formidable evidence. But Gen 1 is not alone. P’s cultic legislation presupposes that night belongs to the preceding day.

Sacrifices: Night Follows Day

Indeed, the laws of the sacrificial rites are patently clear in this regard, with the law requiring that the shelamim offering be consumed before the morning as the parade example:

ויקרא ז:טו וּבְשַׂר זֶבַח תּוֹדַת שְׁלָמָיו בְּיוֹם קָרְבָּנוֹ יֵאָכֵל לֹא יַנִּיחַ מִמֶּנּוּ עַד בֹּקֶר.
Lev 7:15 The flesh of the sacrifice of his thanksgiving peace offering shall be eaten on the day it is offered; none of it shall he leave until morning.[8]

Even the Talmud makes no attempt to deconstruct this scripture, but on the contrary, recognizes that for priests in the sanctuary the night was the sequel to the preceding daylight hours (b. Hul. 83a; b. Tem. 14a):

בקדשים לילה הולך אחר היום
When it comes to sacrifices, night follows day.

The very rhythm of sacrifices is tied to a day beginning at dawn, with the priests first duty being to feed the fire on the altar in preparation for that day’s offerings:

ויקרא ו:ב …זֹאת תּוֹרַת הָעֹלָה הִוא הָעֹלָה עַל מוֹקְדָה עַל הַמִּזְבֵּחַ כָּל הַלַּיְלָה עַד הַבֹּקֶר וְאֵשׁ הַמִּזְבֵּחַ תּוּקַד בּוֹ… ו:ה וְהָאֵשׁ עַל הַמִּזְבֵּחַ תּוּקַד בּוֹ לֹא תִכְבֶּה וּבִעֵר עָלֶיהָ הַכֹּהֵן עֵצִים בַּבֹּקֶר בַּבֹּקֶר וְעָרַךְ עָלֶיהָ הָעֹלָה וְהִקְטִיר עָלֶיהָ חֶלְבֵי הַשְּׁלָמִים.
Lev 6:2 …This is the ritual of the burnt offering: The burnt offering itself shall remain where it is burned upon the altar all night until morning, while the fire on the altar is kept going on it…. 6:5 The fire on the altar shall be kept burning, not to go out: every morning the priest shall feed wood to it, lay out the burnt offering on it, and turn into smoke the fat parts of the offerings of well-being.

Very likely the temple protocol attested all too firmly to priestly practice. No midrash could supplant public knowledge!

Change Afoot in P

As discernibly as the bulk of P bespeaks a day-precedes-night system, Exodus 12:18 and Lev 23:32 reverse that order, making the day begin the previous night. We would venture that these two verses represent a reform that sought to replace P’s older division of days with a night-first model.

The fact that only the Matzot festival and Yom HaKippurim were thus amended may suggest that the reform came about at the eleventh hour just as the Torah text was being canonized. But if circumstances were not propitious for revising all the Torah’s yoms, in the long run it didn’t matter. One way or another, the new system seems to have prevailed, to the degree that remaining traces of P’s former computation of days were explained away so successfully that even Gen 1’s boker was lost in the process.

If we are correct that Exodus 12:18 and Leviticus 23:32 are later interpolations, it might help account for the awkwardness of these verses within their respective contexts. It would also explain why they are positioned after חֻקַּת עוֹלָם summary formulations. Thus at Lev 23:31 we read:

ויקרא כג:לא כָּל מְלָאכָה לֹא תַעֲשׂוּ חֻקַּת עוֹלָם לְדֹרֹתֵיכֶם בְּכֹל מֹשְׁבֹתֵיכֶם.
Lev 23:31 Do no work whatever; it is a law for all time, throughout the ages in all your settlements.

Then we get v. 32 which is no ordinary inclusio. For besides duplicating the instructions of v. 27, “you shall afflict yourselves” (וְעִנִּיתֶם אֶת נַפְשֹׁתֵיכֶם), it goes out of its way to unequivocally revise or recast the timing of the holiday from the tenth to “the ninth at evening till the next evening”.

At Exodus 12 the pattern is the same. The new verse comes after a typical summary formula (12:17),[9] and in the course of repeating v. 15’s law (matzot shall be eaten during the festival) it lays down a time frame in emphatic language that jumps off the page and cannot be missed. The intent is, no doubt, to shift the hour of the festival’s onset from where the rest of the chapter had set it. In other words, “fourteenth at night” is polemicizing with those who think the day starts in the daytime.

Shabbat and Genesis 1

The Sages’ close reading of texts often seems within striking distance of our contemporary critical approach and sometimes they hit the mark. However, megalithic bulwarks held them back when it came to Genesis 1. The mere contemplation of any alternative understanding would have been anathema inasmuch as it could threaten shabbat which, long before the rabbinic era – indeed as far back as Nehemiah – began with nightfall on Friday.

נחמיה יג:יט וַיְהִי כַּאֲשֶׁר צָלֲלוּ שַׁעֲרֵי יְרוּשָׁלַ‍ִם לִפְנֵי הַשַּׁבָּת וָאֹמְרָה וַיִּסָּגְרוּ הַדְּלָתוֹת וָאֹמְרָה אֲשֶׁר לֹא יִפְתָּחוּם עַד אַחַר הַשַּׁבָּת וּמִנְּעָרַי הֶעֱמַדְתִּי עַל הַשְּׁעָרִים לֹא יָבוֹא מַשָּׂא בְּיוֹם הַשַּׁבָּת. יג:כ וַיָּלִינוּ הָרֹכְלִים וּמֹכְרֵי כָל מִמְכָּר מִחוּץ לִירוּשָׁלָ‍ִם פַּעַם וּשְׁתָּיִם. יג:כא וָאָעִידָה בָהֶם וָאֹמְרָה אֲלֵיהֶם מַדּוּעַ אַתֶּם לֵנִים נֶגֶד הַחוֹמָה אִם תִּשְׁנוּ יָד אֶשְׁלַח בָּכֶם מִן הָעֵת הַהִיא לֹא בָאוּ בַּשַּׁבָּת.
Neh 13:19 When shadows filled the gateways of Jerusalem at the approach of the sabbath, I gave orders that the doors be closed, and ordered them not to be opened until after the sabbath. I stationed some of my servants at the gates, so that no goods should enter on the sabbath. 13:20 Once or twice the merchants and the vendors of all sorts of wares spent the night outside Jerusalem, 13:21 but I warned them, saying, “What do you mean by spending the night alongside the wall? If you do so again, I will lay hands upon you!” From then on they did not come on the sabbath.[10]

Thus the rabbis did not probe boker in Genesis 1; it was out of bounds – long deemed a danger zone.

Ibn Ezra’s Curse to Protect the Shabbat

This perceived danger can be highlighted by the aggressive reaction of R. Abraham ibn Ezra (1089-1167) upon coming in contact with Rashbam’s interpretation of Genesis 1 (already mentioned in passing). He pronounced an ominous imprecation on any who would dare promote it, fearing that it argues for a Shabbat beginning in the morning.[11]

Ibn Ezra’s vehemence testifies not to the implausibility of Rashbam’s interpretation, but to its perceived flouting of tradition. At the risk of their tongue and palate agglutinating and their right eye losing its sight (Ibn Ezra’s curse), there are those, the present writer among them, who incline to take the key word boker [=morning] at face value. Hence, the reports of how things unfolded on each creation “day” can be read as chronologically ordered, with morning marking the end of one unit and the start of the next.

Though we would like to sign off by identifying the catalyst that might have triggered the reform,[12] so far all proposals have been too speculative to share, but the quest continues…


September 17, 2018


Last Updated

April 13, 2024


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Dr. Hacham Isaac S. D. Sassoon is a rabbi and educator and a founding member of the ITJ. He studied under his father, Rabbi Solomon Sassoon, Hacham Yosef Doury, Gateshead Yeshivah and received his semicha from the Chief Rabbinate of Israel. He holds a Ph.D. in literature from the University of Lisbon. He is the author of The Status of Women in Jewish Tradition (Cambridge University Press 2011), a commentary on chumash An Adventure in Torah: A Fresh Look Through a Traditional Lens (KTAV 2023), and most recently the co-editor with Rabbi Steven H. Golden of the Siddur 'Alats Libbi (Ktav 2023).