Exodus 24:4-7

4And Moses wrote down all the words of the LORD.

Early the next morning he got up and built an altar at the base of the mountain, along with twelve pillars for the twelve tribes of Israel. 5Then he sent out some young men of Israel, and they offered burnt offerings and sacrificed young bulls as peace offerings to the LORD.

6Moses took half of the blood and put it in bowls, and the other half he splattered on the altar. 7Then he took the Book of the Covenant and read it to the people, who replied, “All that the LORD has spoken we will do, and we will be obedient.”