Aliya Summary: G‑d gave the Israelites several mitzvot: 1) All male Israelite firstborn were henceforth sanctified to G‑d. 2) Eat matzah on Passover. 3) Recount the story of the Exodus at the Passover seder. 4) Bring all male firstborn of kosher as sacrifices. 5) Redeem all male firstborn donkeys for a sheep—which is then brought as a sacrifice. 6) Don tefillin on the head and arm.
If the donkey owner refuses to redeem it, he must destroy it. Although this too is counted among the 613 commandments of the Torah, it is clear that the Torah prefers the owner to redeem it and not resort to the wasteful alternative. Although one can get out of this mitzvah by selling a part interest in the mother donkey to a non-Jew before the firstborn is delivered, the Shulchan Aruch forbids doing so, since the opportunity to do a mitzvah would be lost. The reason the Shulchan Aruch had to warn us not to get out of this mitzvah is that in the previous section it taught the same “legal technicality” (partnership with a non-Jew in the expectant mother) that would succeed in our not having a mitzvah to perform. In one case, kosher animal, it is too problematic without a temple to allow the mitzvah to exist (so to speak). In the other, donkey, the mitzvah can be performed any time, and so it should not be avoided.