QUESTION

Maryland, USA

When putting up a mezuzah on someone else’s behalf, the berakhah is “al keviat mezuzah” instead of the usual “likboa mezuzah.” Same for milah, if parent does it themselves, it’s “lamul et haben” (according to Rambam) but if mohel does it it’s “al hamilah.” Why is there a distinction for some mitzvot, while for others like matzah and maror and lulav, we say “al ha…” even if we ourselves are doing it?

ANSWER

First, that’s only according to Rambam. The practice (at least amongst Ashkenazim) is to always keep