Exodus 24:4-7 (New International Version)

⁴ Moses then wrote down everything the LORD had said.
      He got up early the next morning and built an altar at the foot of the mountain and set up twelve stone pillars representing the twelve tribes of Israel. ⁵ Then he sent young Israelite men, and they offered burnt offerings and sacrificed young bulls as fellowship offerings ^[a] to the LORD. ⁶ Moses took half of the blood and put it in bowls, and the other half he sprinkled on the altar. ⁷ Then he took the Book of the Covenant and read it to the people. They responded, "We will do everything the LORD has said; we will obey."