John Gill Commentary Deuteronomy 17:1

"Thou shalt not sacrifice unto Jehovah thy God an ox, or a sheep, wherein is a blemish, [or] anything evil; for that is an abomination unto Jehovah thy God." — Deuteronomy 17:1 (ASV)

You shall not sacrifice unto the Lord your God any
bullock or sheep wherein is blemish
No sacrifice of any sort, whether burnt offering, sin offering, or peace offering, was to have any blemish in it; typical of the unblemished and immaculate Lamb of God, who, being without sin, offered himself without spot to God, and so could take away the sins of others by the sacrifice of himself; see (Leviticus 22:18–25) ,

[or] any evilfavouredness ;
any sickness or disease upon it of any sort, which made it ill favoured to the sight, or disagreeable to the smell, or however unacceptable for sacrifice:

for that is an abomination to the Lord your God ;
every such blemished and ill favoured sacrifice; see (Malachi 1:8Malachi 1:14) .