Taanit Bechorot
What is the origin of the fast of the firstborn? Why do we fast? Most of the Ashkenazi Rishonim quote it but it's not clearly sourced in the Gemara, it is discussed in מסכת סופרים.
The Gemara records that Rebbe fasted on Erev Pesach but not because he was a bechor but because he was an איסטניס. Does that apply to the reverse scenario (where not eating on Erev Pesach would make the Seder more difficult)?
Do we go by a technical definition of a bechor (which would exclude Kohanim, Leviim, and those born via C-section), or do we say it's a minhag and we don't go by halachic definitions?
How serious is the fast? When is Taanit Bechorim observed in a year in which Erev Pesach falls on Shabbos?
Going to a siyum in place of fasting.
Delivered at the OU Israel Center, April 10th, 2019, 5 Nisan 5779