Albert Barnes Commentary Leviticus 22:8

"That which dieth of itself, or is torn of beasts, he shall not eat, to defile himself therewith: I am Jehovah." — Leviticus 22:8 (ASV)

The pollution in the priests would be especially serious, since they would have to abstain from their sacred functions. Compare Ezekiel 4:14 and Ezekiel 44:31. The general prohibition occurs in Leviticus 11:39, Leviticus 17:15, and Exodus 22:31.