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Taanit 12

Dream fasts.

On today’s daf, the rabbis continue to discuss the laws of personal fasts. While most of Tractate Taanit concerns public fasts that were called in response to some kind of communal emergency — most notably lack of rain — individuals could also choose to undertake personal fasts. Though this practice has largely been abandoned, in rabbinic times these fasts could be observed for any number of reasons, including as a gesture of repentance, for spiritual cleansing, or on the yahrzeit of a loved one or a teacher. 

They could also be undertaken in case of a bad dream, a fast known as a taanit halom — which literally means (you guessed it) “dream fast.” The rabbis believed that dreams could convey profound truths, even messages from another realm. A disturbing dream could be a portentous sign of things to come and fasting was seen as a method of averting whatever evil fate might be in store. 

And so we encounter this story on today’s daf:

Rav Yehoshua, son of Rav Idi, happened to visit the house of Rav Asi. They prepared a third-born calf (whose meat is high quality) for him.

They said to him: Let the Master taste something.

He said to them: I am observing a fast.

They said to him: And let the master borrow and repay the fast. Doesn’t the master hold in accordance with this halakhah that Rav Yehuda said that Rav said: A person may borrow his fast and repay?

Rav Yehoshua, son of Rav Idi, said to them: It is a fast for a dream.

The context for this story is a teaching from Rav Yehuda in the name of Rav that one may “borrow and repay” a fast — that is, if someone cannot fast on the day they intended to, they simply annul the fast and fast on a different day. The story of Rav Yehoshua suggests that a taanit halom is an exception to this rule. 

The Gemara goes on: 

And Rabba bar Mehasseya said that Rav Hama bar Gurya said that Rav said: A fast is effective to neutralize a bad dream like fire is effective for burning chaff.

Rav Hisda said: The fast is effective specifically on that day that one dreamed. 

Unlike other types of personal fasts, a taanit halom must be undertaken on the day one had the dream. It can’t be delayed. This practice is so important, in fact, that it’s even permissible to observe a taanit halom on Shabbat. Enjoying Shabbat is so sacred that every fast day (save for Yom Kippur) is bumped forward a day if it falls out on Shabbat. But if someone had a frightening dream on a Friday night, this rule is suspended and a personal fast is permitted. 

So how does one make up for desecrating Shabbat by fasting? Easy, the Gemara tells us:

Let him sit in observance of another fast, on another day, to atone for his fast on Shabbat.

Read all of Taanit 12 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on November 24th, 2021. If you are interested in receiving the newsletter, sign up here.

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