פירוש על ברכות 39:4

Thirteen schools. There are those who explain that they maintained experts [in Okatzin] in thirteen yeshivot; “thirteen” is not to be taken literally, rather it is a common amplification throughout Talmud, e.g. “thirteen coins” (Chulin 44a). Rashi explains it in a different manner.

The Fourth Order of the Mishnah. The detailed division of the Mishnah is given in an Appendix by Oesterley and Box.

The last Tractate of the Sixth Order.

The disputations between Rab and Samuel are proverbial for their complexity.

Others explain: with thirteen different methods of interpretation. In either case, the intention is that the superiority of earlier generations could not be on the score of learning.

He merely prepared himself to fast and pray for rain. On any occasion of mourning or self-humiliation, the shoes are taken off.