The Midrashim and early commentaries don't mention or comment on the small
mem. Possibly it's an allusion to the fact that the parts of the sacrifices
that were burnt on the altar overnight were consumed gradually, to make sure
that the altar was never left bare, so the fire on the altar was small.
Another possibility: the small mem may be a hint that the fire on the (small)
golden altar was taken from the main altar; the Midrash derives this from the
last four words of this verse. The Talmud (Yoma 45a) tells us that there were
three fires on the main altar, and that the word "mokdah" refers to the largest
of them. The commentary "Oznayim la-Torah" by Rabbi Zalman Sorotzkin suggests
that this is why the "mem" in "mokdah" is small, because the greater one is,
the more one must humble oneself (Rashi on Berachos 34b s.v. "Kohen gadol").
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