Exodus 24:5-6, 8

Then Moses sent young Israelite men to offer whole burnt offerings and to sacrifice young bulls as fellowship offerings to the LORD. Moses put half of the blood of these animals in bowls, and he sprinkled the other half of the blood on the altar.

Then Moses took the blood from the bowls and sprinkled it on the people, saying, “This is the blood that begins the Agreement, the Agreement which the LORD has made with you about all these words.”