15 The meat of the peace offering of thanksgiving must be eaten on the same day it is offered. None of it may be saved for the next morning. 16 "If you bring an offering to fulfill a vow or as a voluntary offering, the meat must be eaten on the same day the sacrifice is offered, but whatever is left over may be eaten on the second day. 17 Any meat left over until the third day must be completely burned up. 18 If any of the meat from the peace offering is eaten on the third day, the person who presented it will not be accepted by the Lord . You will receive no credit for offering it. By then the meat will be contaminated; if you eat it, you will be punished for your sin.
Matthew Henry's Commentary on Leviticus 7:15-18
Commentary on Leviticus 7:11-27
(Read Leviticus 7:11-27)
As to the peace-offerings, in the expression of their sense of mercy, God left them more at liberty, than in the expression of their sense of sin; that their sacrifices, being free-will offerings, might be the more acceptable, while, by obliging them to bring the sacrifices of atonement, God shows the necessity of the great Propitiation. The main reason why blood was forbidden of old, was because the Lord had appointed blood for an atonement. This use, being figurative, had its end in Christ, who by his death and blood-shedding caused the sacrifices to cease. Therefore this law is not now in force on believers.