Exodus 24:4-7
4And Moses wrote all the words of the LORD, and rose up early in the morning, and builded an altar under the hill, and twelve pillars, according to the twelve tribes of Israel. 5And he sent young men of the children of Israel, which offered burnt offerings, and sacrificed peace offerings of oxen unto the LORD. 6And Moses took half of the blood, and put it in basons; and half of the blood he sprinkled on the altar. 7And he took the book of the covenant, and read in the audience of the people: and they said, All that the LORD hath said will we do, and be obedient.