The gemara (27b-28a) recounts how different groups of students asked their rebbeim why they merited to live such long lives. According to the Meiri, each Amora explained to his students where he went beyond the letter of the law to receive this reward.

When his students asked him, Rav Nuchunia ben Hakana explained that he merited a long life because “he never allowed his friend’s curse to ascend on his bed.” In other words, every night before he went to bed, he forgave anyone who had insulted or harmed him over the day. The rishonim ask that this seems to contradict another gemara in Yoma (23a), which states that a talmid chacham should not forgive anyone until he asks for forgiveness.

The Rambam (Egypt, 1135-1224, Talmud Torah 7:13) resolves this apparent contradiction as follows: “This was the way of the early pious people; they would listen to their humiliation and not respond. Not only that, but they would forgive the people who would humiliate them… This is the way of talmidei chachamim that is fitting to follow. When is this stated? When they embarrassed or disgraced him in private, however, if they embarrassed or disgraced a talmid chacham in public, it is forbidden for him to forgo his honor, and if he forgives him, he is punished because this is a disgrace of the Torah.” If someone privately insults a talmid chacham, he can, and should, forgive him because it is only his private honor; however, in pubic, the talmid chacham represents the Torah, and an insult to him is an insult to the Torah. In this case, according o the Rambam, he may not forgive the person who insulted him until he asks for forgiveness.

In another discussion, when the students asked Rav Zeira why he merited a long life, he responded that he had the unique merit of never sleeping in a beis medrash. The Shulchan Aruch (OC 151:3) paskens that while a person cannot sleep in a shul, he may sleep in a beis medrash. The Vilna Gaon explains that the source for this halacha is our gemara. This is why Rav Zeira was so proud that he never slept in a beis medrash, because it is not actually forbidden. Rav Zeira went beyond the letter of the law in his respect for batei medrash, and was therefore rewarded with an especially long life.

The Shach (Poland, 1621-1662, YD 246:15) explains the shulchan aruch’s ruling that it is only permitted to take a short, unplanned nap, but a long, permanent sleep is forbidden even in a beis medrash. According to the Shach, Rav Zeira was rewarded, because he did not even take a short nap in a beis medrash. The sefer T’Hilah L’Yonah points out that the Mishnah Berurah (Poland, 1838-1933, 151:16) rules that a talmid chacham who spends almost his whole day learning may even take a long, permanent sleep in the beis medrash. According to this, Rav Zeira was rewarded with a long life for both not taking a short nap nor a long sleep, because both were actually permitted for him to do.