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.

15-17. the flesh of the sacrifice of his peace offerings … shall be eaten the same day that it is offered—The flesh of the sacrifices was eaten on the day of the offering or on the day following. But if any part of it remained till the third day, it was, instead of being made use of, to be burned with fire. In the East, butcher-meat is generally eaten the day it is killed, and it is rarely kept a second day, so that as a prohibition was issued against any of the flesh in the peace offerings being used on the third day, it has been thought, not without reason, that this injunction must have been given to prevent a superstitious notion arising that there was some virtue or holiness belonging to it.