Charles Ellicott Commentary Jeremiah 7:21

"Thus saith Jehovah of hosts, the God of Israel: Add your burnt-offerings unto your sacrifices, and eat ye flesh." — Jeremiah 7:21 (ASV)

Put your burnt offerings. —that is, “Add one kind of sacrifice to another. Offer the victim, and then partake of the sacrificial feast. All is fruitless, unless there are the true conditions of acceptance, repentance, and holiness.”