If a Choleh says "I can [fast]'', and a doctor says that he cannot, we heed the doctor. If the doctor says "he can'', and the Choleh says that he cannot, we heed the Choleh.

Question: We ask only when the Choleh says "I can'', and a doctor says "I do not know''!

Answer (R. Avahu citing R. Yochanan): This is like Safek Nefashos (mortal danger), and every Safek Nefashos overrides Shabbos [which is punished by stoning, and all the more so Yom Kipur, which has only Kares].

(Mishnah): One who was seized by Bulmus (he is in mortal danger due to hunger), we feed him even Tamei matters until his vision returns.

If one was bitten by a rabid dog, we do not feed him from its Chatzer Kaved (the Chelev on the liver). R. Masyah ben Charash permits.

Further, R. Masyah ben Charash says that if one's throat hurts, we cast a potion in it on Shabbos, for it is Safek Nefashos, for every Safek Nefashos is Docheh Shabbos.

If a house caved in on someone, and it is a Safek whether he was there or not, and [if he was there] it is a Safek whether he is alive or dead, and it is a Safek whether or not he is a Nochri or Yisrael, we uncover him. If we find that he is alive, we [totally] uncover him. If we find that he is dead, we leave him.

(Gemara) Question: What is the source that we feed him pressed figs and raisins of Terumah? [A Mitzri had not eaten for three days,] "va'Yitnu Lo Pelach Develah u'Shnei Tzimokim.''

(Rav Chunah): Twenty-four Esronim (i.e. all the Lechem ha'Panim; each of the 12 loaves was two Esronim, the volume of more than 86 eggs) that David ate, he ate in his hunger [of Bulmus. If not for the danger, a Zar may not eat Lechem ha'Panim.]

R. Yochanan reached such a state, and ate everything found in front of him [even Isur]. They applied to him "ha'Chachmah Techayeh Ba'aleha.''

(Beraisa): We feed him the lightest Isur [that will revive him]. If there is [only] Terumah and Neveilah, we feed to him Terumah. If there is Tevel and Shevi'is, we feed to him Shevi'is. If there is Chalah and Orlah, it is a question [which we feed to him].

Question (R. Yosah, to R. Ba): Terumah is an Aveirah of Misah [bi'Ydei Shamayim, for a Zar or Tamei who eats it], and Neveilah is a Lav, and you say so [that Terumah is the lighter Isur]?!

Answer: [The Tana] holds like the opinion that [in Bayis Sheni, the Torah did not obligate separating tithes, just] they accepted on themselves [to separate Terumah and] Ma'aseros.