Exodus 24:3-5

3Moses went and he told the people all the Lord's commands and his teaching. The people answered together, ‘We will do everything that the Lord has told us.’

4Then Moses wrote down everything that the Lord had said. Early the next morning, Moses built an altar at the bottom of the mountain. Then he put up 12 stone pillars. Each pillar stood there for one of Israel's 12 tribes.

5Moses sent young Israelite men to burn animals there, as offerings to the Lord. They also killed young bulls as friendship offerings to the Lord.