Taanit

With reference to what you said that one may fast for a matter of hours this only applies if [the man concerned] had not tasted anything until the evening. Abaye said to him: This is then a full fast! — This speaks of a case where the fast was only an after thought.1 R. Hisda further said: A fast over which the sun has not set cannot be deemed a fast. An objection was raised against this. The men of the Mishmar fast but do not complete [the day]. [There fasting] is merely in order to afflict themselves [in sympathy with the community].2 Come and hear: R. Eleazar b. Zadok said: I am a descendant of Sena'ah3 of the tribe of Benjamin; once the [fast of] the ninth of Ab fell on the Sabbath and we postponed it until the day after the Sabbath and we fasted but did not complete the fast because it was our festive day!4 — There too the fasting was merely in order to afflict themselves [in sympathy with the community]. Come and hear: R. Johanan [once] said: ‘I will fast until I return home’! — There he said this merely in order to evade the hospitality of the house of the Nasi.5 Samuel said: A fast which one does not undertake before sunset on the previous day is not deemed to be a fast. But what if a man does observe such a fast? — Rabbah b. Shila replied: It may be compared to a pair of bellows filled with wind.6 At what time should one undertake such a fast? — Rab said: During the time that one may read the Afternoon Service, and Samuel said, In the course of the Afternoon Tefillah. R. Joseph said: The view of Samuel appears the more reasonable, since it is written in the Scroll of Fasts: Therefore any man who has been subject to a fast previous to this [i.e. , the incidence of these festive days] should build himself7 [by an undertaking]. Does this not refer to an undertaking made during prayer?8 — No; this only denotes that he is forbidden [to break his fast because of his previous undertaking]. R. Hiyya and R. Simeon b. Rabbi differ on this question. One reads9 yesar10 [‘he should bind himself by his under-taking’] and the other reads, yeaser11 [he is forbidden, i.e., to break his fast]. The one who reads, yesar, justifies his view in the way we have just stated, but the one who reads, yeaser, what does this mean? — It has been taught in the Scroll of Fasts: Any man who is subject to a fast previous to this [incidence of these festive days] is forbidden [to break his fast]. How is this to be understood? If a man undertook to fast on Mondays and Thursdays throughout the year and any of the festive days enumerated in the Scroll of Fasts happens to fall on those days, then if his vow was made previous to our decree his vow overrides our decree, but if our decree was made before his vow then our decree overrides his vow. Our Rabbis taught: Until when may one eat and drink [on the night preceding a fast]? Until the rise of dawn; this is the opinion of Rabbi. R. Eliezer b. Simeon says: Until cock crow. Abaye said: This only holds good where a man had not yet finished his meal, but if he had finished his meal he may not eat again. Raba raised an objection against this: If one had completed his meal and rose from the table, he may eat further! — There it speaks of the case where he had not yet removed the [table].12 Some say, Raba said: This holds good only when he has not gone to sleep, but if he has gone to sleep he may not eat again. Abaye raised an objection against this: If one had gone to sleep and then got up he may eat again! — There it speaks of the case where he was merely dozing. What constitutes dozing?-R. Ashi replied: have a meal and decides that he would end the day without food so as to make it constitute a fast. In such special circumstances the fast is a valid one, though the man had not explicitly undertaken it on the day previous (V. Rashi).