Exodus 24:3-7

And Moses came and told the people all the words of Jehovah, and all the ordinances: and all the people answered with one voice, and said, All the words which Jehovah hath spoken will we do. And Moses wrote all the words of Jehovah, and rose up early in the morning, and builded an altar under the mount, and twelve pillars, according to the twelve tribes of Israel. And he sent young men of the children of Israel, who offered burnt-offerings, and sacrificed peace-offerings of oxen unto Jehovah. And Moses took half of the blood, and put it in basins; and half of the blood he sprinkled on the altar. And he took the book of the covenant, and read in the audience of the people: and they said, All that Jehovah hath spoken will we do, and be obedient.