15 'The flesh of the sacrifice of his peace offering for thanksgiving shall be eaten the same day it is offered. He shall not leave any of it until morning. 16 But if the sacrifice of his offering is a vow or a voluntary offering, it shall be eaten the same day that he offers his sacrifice; but on the next day the remainder of it also may be eaten; 17 the remainder of the flesh of the sacrifice on the third day must be burned with fire. 18 And if any of the flesh of the sacrifice of his peace offering is eaten at all on the third day, it shall not be accepted, nor shall it be imputed to him; it shall be an abomination to him who offers it, and the person who eats of it shall bear guilt.
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.