Parashas Bo · Shemos 12:7 · TT note 2
Torah Temimah on Shemos 12:7, note 2 (on שְׁתֵּי הַמְּזוּזֹת) points to Menachos 34a (R’ Akiva’s binyan av).
Sefaria — Exodus 12:7
Sefaria — Torah Temimah on Exodus 12:7
Sefaria — Menachos 34a
E-Daf — Menachos 34a
English: Rabbi Akiva says: It is not necessary [to use the other derashah]; when it says “on the lintel and on the two doorposts,” why say “two”? This builds a prototype: wherever Scripture says “mezuzot,” it means only one, until the text specifies two for you.
Binyan av from this verse: the ordinary mitzvah of mezuzah requires one post unless Scripture specifies two.
The extra word “two” here teaches that elsewhere “mezuzot” does not require two doorposts for the mitzvah of mezuzah.