Exodus 24:4-8

And Moses wrote down all the words of the Lord. Then he got up early in the morning, and built an altar at the foot of the mountain with twelve memorial stones for the twelve tribes of Israel.

And he sent young men of the sons of Israel, and they offered burnt offerings and sacrificed bulls as peace offerings to the Lord.

Moses took half of the blood and put it in basins, and the other half of the blood he sprinkled on the altar.

Then he took the Book of the Covenant and read it as the people listened; and they said, “All that the Lord has spoken we will do, and we will be obedient!”

So Moses took the blood and sprinkled it on the people, and said, “Behold the blood of the covenant, which the Lord has made with you in accordance with all these words.”