And the 61st mitzvah is that we are commanded that every sacrifice that we bring must be complete, i.e. clean of any blemish as defined by Scripture and the Oral Tradition.1

The source of this commandment is G‑d's statement2 (exalted be He), "It must be unblemished in order to be acceptable."

The Sifra says, "The verse, 'It must be unblemished in order to be acceptable,' constitutes a positive commandment." From the verse,3 "These [sacrifices] and their libations must be without blemish for you [to present them]," our Sages derived that the wine used for libations, their oil, and their flour must be the finest and free of any imperfection.4

The details of this mitzvah are explained in the eighth chapter of Menachos.5