Exodus 24:3-8

Then Moses went down to the people and repeated all the instructions and regulations the LORD had given him. All the people answered with one voice, “We will do everything the LORD has commanded.” Then Moses carefully wrote down all the LORD’s instructions. Early the next morning Moses got up and built an altar at the foot of the mountain. He also set up twelve pillars, one for each of the twelve tribes of Israel. Then he sent some of the young Israelite men to present burnt offerings and to sacrifice bulls as peace offerings to the LORD. Moses drained half the blood from these animals into basins. The other half he splattered against the altar. Then he took the Book of the Covenant and read it aloud to the people. Again they all responded, “We will do everything the LORD has commanded. We will obey.” Then Moses took the blood from the basins and splattered it over the people, declaring, “Look, this blood confirms the covenant the LORD has made with you in giving you these instructions.”