Charles Ellicott Commentary Leviticus 22:21

"And whosoever offereth a sacrifice of peace-offerings unto Jehovah to accomplish a vow, or for a freewill-offering, of the herd or of the flock, it shall be perfect to be accepted; there shall be no blemish therein." — Leviticus 22:21 (ASV)

A sacrifice of peace offerings: (See Leviticus 3:1.)

To accomplish a vow: In fulfilment of a vow made in time of impending danger (Genesis 28:20–22; Jonah 1:16, and similar passages).

Freewill offering: Generally brought in acknowledgment of mercies received.