Deuteronomy 27:5-7
5
There you shall build an altar to Yahweh your God, an altar of stones: you shall lift up no iron [tool] on them.
6
You shall build the altar of Yahweh your God of uncut stones; and you shall offer burnt offerings thereon to Yahweh your God:
7
and you shall sacrifice peace offerings, and shall eat there; and you shall rejoice before Yahweh your God.