Exodus 24:4-7

And Moses wrote all the words of the LORD. And he rose early in the morning, and built an altar at the foot of the mountain, and twelve pillars according to the twelve tribes of Israel. Then he sent young men of the children of Israel, who offered burnt offerings and sacrificed peace offerings of oxen to the LORD. And Moses took half the blood and put it in basins, and half the blood he sprinkled on the altar. Then he took the Book of the Covenant and read in the hearing of the people. And they said, “All that the LORD has said we will do, and be obedient.”