Some operations require fasting an entire day. I understand that one is not allowed to fast on Shabbat (except on Yom Kippur.)

The scenario:

Let's say a patient needs has had knee osteoarthritis. It is not painful, but the patient can't walk easily. He goes to the doctor just before Shabbat, and the doctor has recommended surgery. The doctor recommends doing it on Sat. night since he is in the hospital anyway on Saturday, and his schedule is filled for a few weeks afterwards, and he doesn't want to wait until the next available slot, which is a long time away. The patient's situation is not life threatening, and his condition is not painful, nor would things deteriorate if he waited until the next available slot which is on a Wednesday 2 month's later. However, the doctor recommends things be done the next day, as he doesn't want the patient to feel uncomfortable.

Prior to the operation, he must fast 24 hours -no food, no water or anything whatsoever. Shabbat starts at 5 PM, is over next day 6:15, operation is at 6:30 (patient lives a few minutes from the hospital.) OK, so he is supposed to start fasting from 6:30 PM Fri. night. Technically, he would be able to eat something at the start of Shabbat, except for one thing. The doctor says that he must immediately take some strong med upon leaving his office. He takes it, on the way home from the appointment, he feels nauseous and can't eat anything. 6:30 PM Fri. night arrives, so he must begin fasting.

Knowing that he must fast all day on Shabbat, but based on what the patient and doctor deem to be better treatment, can he still schedule the procedure on Motzaei Shabbat?

  • You mentioned it's not a life-threatening situation, but what kind of situation is it? Choleh sheyesh bo sakanah? Choleh sheayn bo sakanah? Meychush beAlma?
    – Daniel
    Commented Sep 4, 2015 at 16:28
  • @Daniel Good point! I edited. I'm uncertain what category my sit. is in.
    – DanF
    Commented Sep 4, 2015 at 16:37
  • Is it really not an option to have perhaps just a sip of water in the morning? Or maybe the operation can be scheduled in the late morning on Sunday or later to give the patient some time to eat Shabbos morning and then still go 24 hours without food.
    – Daniel
    Commented Sep 4, 2015 at 16:43
  • @Daniel I have oral surgery soon. My doctor said, not even water beforehand. My case is an exception as I have to take some meds in the morning but only enough H2O to swallow the meds. So, assume that the answer to your question is "no". And assume that the operation must be done in the early A.M. as that's when the doctor can get all his assistants. (Unlike the doctor, he's getting them at the end of their night shift!)
    – DanF
    Commented Sep 4, 2015 at 16:49
  • 2
    I've never heard of a surgery one day (e.g. Sunday 8:00 in the morning) that requires fasting the entire previous day (from Friday 8:00 in the evening: that's 36 hours!). But, then, there many things in existence of which I've never heard.
    – msh210
    Commented Sep 4, 2015 at 17:46

1 Answer 1


R' Elazar said in the name of R' Yossi Ben Zimra:

"Whoever engages in fasting on the Sabbath, they rip up on his behalf (even) a decree of 70 years of evil. But even so, they return and exact punishment from him for (neglecting) the law of enjoying the Sabbath." What should he do to fix this? Rav Nachman Bar Yitzchak said: "Let him fast again for (the sin) of the (first) fast." (Brachos, 31b ,near the bottom)

Although in general we pasken that one is not allowed to fast on Shabbos, and most Rishonim and Poskim equate this Gemara with two similar passages (see Shabbos 11a and Taanis 12b which specifically talks about fasting on Shabbos for a bad dream only), there is still basis to allow your fast before the operation in your situation.

The basic source to follow up on, besides the Gemara, is Tur/and Shulchan Aruch 288 with commentaries. It does seem pretty clear that people, especially nowadays, should not fast on Shabbos (some Poskim even say we should no longer fast for a bad dream at all). (However, by reading all comments you get the feeling that small exceptions linger; like fasting on Shabbos Rosh HaShannah for instance according to some.)

Our Gemara above, does not mention a fast for a bad dream. It seems on its face to say that anyone who decides to fast on Shabbos (dream or no dream) benefits (and loses). Rashi here says that the fact someone is suffering by losing all pleasure when everyone around him is rejoicing helps annul the decree. Rashi does not mention that a dream is involved at all.

I think the Ritva, also seems to hold this Gemara is not focused on a bad dream. Rather, it is the fact that a person decides to be so serious with himself and his low spiritual state, that he wants to genuinely take off a Sabbath (when everyone else takes it easy) and focus on returning to Hashem and His service wholeheartedly. Such a man truly desrves help to reach a higher spiritual level and is granted the gift of having any strong evil decree ripped up.

Even according to most Poskim, who say it is only a bad dream that one may fast over on Shabbos, you can still fast for the operation based on their principle. The reason one is allowed to fast for a bad dream on Shabbos, is because the fast will help him repent quickly, and thereby atone and cancel the ill dream's decree. Therefore, the act of fasting is actually counted as ENJOYING Shabbos, because it relieves anxiety! (see Rashba and others)

So follow my logic please. You can take the deteriorating situation with the leg as a message from heaven. If after introspection, it spurs you on to decide to utilize that Sabbath for prayer and learning in repentance, you have halachic basis to do so if you look forward to enjoying a raised spiritual level.

In combination, it is obvious that guaranteeing your doctor will be there now (who knows for sure if he will be back in two months right?) and guaranteeing the problem (although not immediately painful and life threatening) will not surprise you or get worse in two months (doctors' diagnoses are not infallible right?) is certainly a legitimate halchic concern.

In further combination, we have the Gemara in Shabbos 151b, see also Yoma 85b) R. Shimon ben Gamliel said, "We violate Shabbos for a one day old baby. The Torah said to violate one Shabbos for him so that he may observe many Shabbasos."

By that logic, we can say that you should avoid one enjoyment of one Shabbos by fasting, so you can relieve the discomfort of spending 8 or more Shabosos with a bad leg.

(The Orh HaChayim also brings the opinion of the Ma'abit, who says that fasting on Shabbos is really only prohibited for 24 hours straight (sundown to sundown). So if you can break it in any way on Shabbos, you have technically not violated the prohibition of fasting on Shabbos. However, although a Taanis Cholom (for a bad dream) is only from morning to night, I am not sure if our interpretation of our Gemara in brachos 31b is for only half a day as well. It sounds like it is the whole day (24hrs) so breaking it would be counterproductive anyway?)

Finally, if you had recently fasted on Yom Kippur, and your Shabbos is a few days later, you might think that it is silly to fast based on personal repentance ala 31b, because you already reached the pinnacle of spirituality a few days ago!?

I remember a story from Yeshiva many years ago about R' Saadia Gaon. He was staying by a house as a guest, but the host was not informed about who he was hosting. When the host found out he begged the Rav forgiveness for not treating him better. Rav Saadia protested that he was treated very well! The host said, but if I knew who you really really were...I would have realized to treat you even better!

Rav Saadiah cried and said...Hashem, yesterday I thought I knew who You were, but today I became aware of how much greater you really are! How much teshuvah I must do to make up for my neglect yesterday in honoring You as my Creator!

So you can even achieve greater repentance and rip up decrees even a few days after Yom Kippur too.

However, if you do it, you should fast again on a later date for missing Shabbos enjoyment, (I believe 288 shows that the make-up is from sun-up to sundown only)and you should be humble and try to not let anyone know, if possible.

I hope this helps, :)

  • This is definitely bounty-worthy. I'd like to see what other answers may appear before deciding on it. G'mar Chatimah Tovah.
    – DanF
    Commented Sep 21, 2015 at 21:57
  • @ DanF TY- glad you liked it :) Gmar chatimah Tovah, may you be granted your heart's desires Commented Sep 22, 2015 at 1:52
  • @ DanF TY, glad it helped BH Commented Sep 24, 2015 at 19:28

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