Yeshayahu haKohen Hollander asked:
Dear Rabbi, how can the Gemara suggest that the question of Rabbi Hiyya bar Avin applies to the dilemma of who takes precedence: today's Mussaf or tomorrow's Tamid? In this case the rule Ein Maavirin Al HaMitsvoth and Mitsva Habaa Leyadcha al Tahmitsena should apply, and of course we should do the Mussaf!
Bye the way - what is the difference between these two rules?
thank you -
Yeshayahu haKohen Hollander
The Kollel replies:
"Mitzvah ha'Ba'ah lYadcha Al Tachmitzenah" is a requirement for Zerizus, and says nothing about precedence. "Ein Ma'avirin Al ha'Mitzvos" is said where both will eventually be done, but the question is which should be done first. However, when only one can be done, we must deal with which Mitzvah has precedence.
D. Zupnik