In the midst of the Gemara’s discussion of inheritance laws, the Gemara segues to a discussion on the importance of having children.
Rabbi Yoḥanan quotes Rabbi Shimon bar Yoḥai as teaching that God is filled with evra – wrath – at someone who does not have a child who will inherit him. This teaching is based on the parallel language usage in the laws of inheritance (Bamidbar 27:8), where it says ve-ha’avartem et naḥalato, and the passage in Tzefaniah (1:15) where we find a description of a “day of anger” – yom evra ha-yom ha-hu.
The Gemara continues in its teaching that the actual intent of Rabbi Shimon bar Yoḥai is a matter of dispute between Rabbi Yoḥanan and Rabbi Yehoshua ben Levi, one of whom believes that he was referring to someone who does not have an actual child, and the other who understands the reference as talking about someone who does not have a student to follow in his path.
Rabbeinu Gershom explains the second approach as referring to a person who refuses to teach Torah to others, and we can well understand why such a person deserves to have the wrath of God directed at him. In a similar fashion the Ramah explains the first approach as referring to someone who chooses consciously to refrain from having children. Nevertheless, some point to the fact that the continuation of the Gemara appears to apply this even to someone who had children and lost them. In an attempt to establish which position Rabbi Yoḥanan took and which Rabbi Yehoshua ben Levi took, the Gemara tells the story of how Rabbi Yoḥanan would show to others the bone of his tenth child – all of whom had died. The point of the Gemara is that Rabbi Yoḥanan was not embarrassed to let people know that he had no living children, so it must be he who said the verse referred to someone who does not leave behind a student.