Exodus 24:4-6

New Revised Standard Version, Anglicised

⁴ And Moses wrote down all the words of the Lord. He rose early in the morning, and built an altar at the foot of the mountain, and set up twelve pillars, corresponding to the twelve tribes of Israel. ⁵ He sent young men of the people of Israel, who offered burnt-offerings and sacrificed oxen as offerings of well-being to the Lord. ⁶ Moses took half of the blood and put it in basins, and half of the blood he dashed against the altar.