494. You Mean Like Acne?: The prohibition against offering an animal with a temporary blemish
You shall not slaughter for Hashem an ox, a lamb or a goat in which there is any blemish… (Deuteronomy 17:1)
An animal with a physical defect could not be used as a sacrifice even if the blemish is of a temporary nature. The reason for this is as we discussed in Mitzvah #286: for use in the Temple service, something must be of the highest quality. A blemished animal is inferior and would decrease the prestige of the service. This would in turn fail to accomplish the intended relationship between God and the person bringing the offering.
An animal with a permanent blemish may be redeemed but an animal with a temporary blemish may not. The animal with a temporary defect must remain in abeyance to see if it overcomes its blemish or becomes permanently disqualified. At that time, the proper course of action is then taken.
This law applies in Temple times to both kohanim and non-kohanim, both men and women, because anyone was able to perform the slaughter of a sacrifice. It is discussed in the Midrash in the Sifre. This mitzvah is codified in the Mishneh Torah in the first chapter of Hilchos Issurei HaMizbei’ach and is #95 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos.