The Peace Offering was a meal that was shared with the Lord, the priests, and sometimes the common Israelites. The worshipper was to bring a male or female oxen, sheep, or a goat.
The ritual was closely compared to the burnt offering up to the point of the actual burning where the animal’s blood was poured around the edges of the altar. The fat and entrails were burned and the remainder was eaten by the priests and (if it was a free-will offering) by the worshippers themselves. This sacrifice of praise and thanksgiving was most of the time a voluntary act.
The Peace offerings included unleavened cakes. The priests ate all except the memorial portion of the cakes and certain parts of the animal on the same day the sacrifice was made, and when the worshipper joined in and the offering was free-will the worshipper could eat for 2 days of the whole animal except the breast and the right thigh which were eaten by the priests.
Jacob and Laban offered a peace offering when they made their treaty (Gen 31:43 NKJV). It was required to make offerings while making a vow of one’s life to God and thanking Him with praise while free-will offerings were voluntary.