Welcome to a new cycle of Mishnah Yomis. These lessons are inspired by the shiurim of Rabbi Dovid Spetner, and we look forward to your joining us through all of Shas, with Hashem's help. We begin with Maseches Berachos, chapter 1, mishnah 1.
The beginning of the time for the evening Shema:
The mishnah opens with a question: "Me'eimasai korin es Shema b'arvis?" - from what hour at night may one begin reciting the evening Shema? And it answers: "Mi'sha'ah shehakohanim nichnasim le'echol bisrumasan" - from the hour when kohanim are permitted to eat Terumah. A kohen who became tamei and immersed in a mikvah is not purified for eating Terumah immediately upon his immersion; he must also wait for nightfall, and only after sunset may he eat Terumah.
The Gemara derives this from the verse dealing with a kohen who comes to eat Terumah, which teaches that first the sun must set - "v'taher". According to the Gemara, this word does not refer to the purification of the kohen, but to the sun itself: the sun becomes completely clear, meaning the time of nightfall, when darkness has taken hold and the stars have come out. It emerges that nightfall is the earliest time at which one can fulfill the obligation of reciting Shema.
Until when may Shema be recited?
The mishnah continues along the same line and asks until when one may recite it, and on this point the Tannaim disagree:
Rabbi Eliezer - "ad sof ha'ashmurah harishonah": The Gemara explains that the night is divided into three parts, corresponding to the groups of angels in heaven who sing praise to the Holy One, Blessed is He, and the first watch ends at the close of the first third of the night. This is how Rabbi Eliezer understands the wording of the verse "uv'shochbecha" - the hour when people go to sleep, which is the first third of the night.
The Sages - until midnight: Shema may be recited until the midpoint of the night. We will soon see what this opinion is based upon.
Rabban Gamliel - until dawn: From the moment the light begins to rise in the east, even before the sun has risen, it is no longer the time for reciting Shema. In his view, the verse refers to the entire span of time during which people are asleep, and not to the hour at which they go to sleep.
In practice, as we will see shortly, even the Sages hold this way in their understanding of the verse; they said "until midnight" only as a protective measure - to safeguard a person from missing the time altogether.
The incident with Rabban Gamliel's sons:
The mishnah illustrates this with an incident: the sons of Rabban Gamliel, who held that the time extends until dawn, returned from a wedding feast after midnight and said to him, "We have not recited Shema." He answered them: "Im lo alah amud hashachar - chayavim atem likros" - if dawn has not yet arrived, you are obligated to recite it. And he added: not only that, but wherever the Sages said that a particular act may be done only until midnight - "mitzvasan ad sheya'aleh amud hashachar" - and the Sages set midnight only as a safeguard, so that a person should not let the time slip away.
The Gemara explains the depth of the exchange between Rabban Gamliel and his sons: Rabban Gamliel himself recognized that his own opinion, permitting recital until dawn, was a minority opinion, and that his sons were bound to follow the majority - until midnight - even though their father disagreed. Their question to their father was, then, what the basis of the Sages' position is:
Do the Sages disagree with Rabbi Eliezer about the measure of the time when people go to sleep - Rabbi Eliezer says a third of the night, and they say half the night?
Or do they hold like your view, that the verse refers to the entire span during which a person sleeps, and they said "midnight" only as a safeguard? And if their entire reason is a safeguard, then we, who erred and passed the safeguard, are still obligated to recite.
Rabban Gamliel's answer was that the Sages agree with him in their understanding of the verse, that it refers to the entire span during which people are asleep, and that "midnight" is nothing but a safeguard. Therefore, since you missed the safeguard, the obligation to recite remains in force.
Further examples of mitzvos whose time is all night:
Burning the fats and limbs: The burning of the fats and limbs of the olah offerings that were brought that day - "mitzvasan ad sheya'aleh amud hashachar". Most commentators understand that this is not an example of the safeguard of midnight, since no safeguard was set in this halachah; the Rambam, however, holds that a safeguard was set here as well.
Offerings eaten for one day: All offerings that are eaten for one day, meaning that day and the night that follows, may by law be eaten until dawn, except that the Sages said that they should not be eaten after midnight.
And why did the Sages say "until midnight"? The mishnah answers: "kedei leharchik adam min ha'aveirah" - in order to distance a person from transgression. This applies in both cases:
Regarding the offerings: Were he to eat them after dawn, he would be liable for the prohibition of nosar - eating the meat of an offering after its time.
Regarding Shema: He would miss the time for reciting Shema and lose the mitzvah.
The Sages therefore distanced a person from the pitfall and limited the time until midnight.
In summary: In this mishnah we learned that the time for the evening Shema begins from the hour when kohanim enter to eat their Terumah, that is, from nightfall, as derived from the word "v'taher," which refers to the clearing of the sun. As to the end of the time, they disagreed: Rabbi Eliezer - until the end of the first watch, the Sages - until midnight, and Rabban Gamliel - until dawn. We examined the incident with Rabban Gamliel's sons and the Gemara's explanation that even the Sages concede that by law the time extends until dawn, and that they said "until midnight" only as a safeguard - in order to distance a person from transgression, both from the prohibition of nosar with offerings and from missing the mitzvah of reciting Shema.