Exodus 24:4-6
Exodus 24:4-6 MSG
Then Moses wrote it all down, everything GOD had said. He got up early the next morning and built an Altar at the foot of the mountain using twelve pillar-stones for the twelve tribes of Israel. Then he directed young Israelite men to offer Whole-Burnt-Offerings and sacrifice Peace-Offerings of bulls. Moses took half the blood and put it in bowls; the other half he threw against the Altar.