Charles Ellicott Commentary Exodus 20:24

"An altar of earth thou shalt make unto me, and shalt sacrifice thereon thy burnt-offerings, and thy peace-offerings, thy sheep, and thine oxen: in every place where I record my name I will come unto thee and I will bless thee." — Exodus 20:24 (ASV)

An altar of earth you shall make to me. —The earliest altars were, naturally, either of earth or of unhewn stones gathered into a heap, since these could be constructed with little labour and without tools. But, as civilisation advanced, more elaborate structures took the place of the primitive ones. It became usual to erect altars of hewn stone, adorned with carvings more or less rich, among which human and animal forms might often be introduced. We must understand the command given here, and that of Exodus 20:25, as intended to forbid structures of this latter kind, which, if allowed, might have led to idolatry.

Your burnt offerings and your peace offerings. —Sacrifice began soon after Paradise was left (Genesis 4:3–4), and soon became a universal practice. Noah offered sacrifice on leaving the ark (Genesis 8:20); and in the family of Abraham the rite was an established one (Genesis 12:7; Genesis 15:9; Genesis 22:7; Genesis 26:25; Genesis 31:54, and other passages).

Egyptians, Assyrians, Babylonians, Persians, Phoenicians, Greeks, Romans, Scythians, Celts, Germans, all equally regarded sacrifice as a main element of their religion. If the Hebrews had not offered actual sacrifices during their oppression in Egypt, they had, at any rate, maintained the wish to offer them, and it was (primarily) for the purpose of sacrificing that they had left Egypt. The legislation assumes that they are acquainted with the difference between “burnt offerings” and “peace offerings,” and desirous of offering both kinds.