Exodus 24:6-8

So Moses took the blood and sprinkled it upon the people and said: ‘Here is the blood of the covenant that Jehovah has concluded with you as respects all these words.’”

On the other hand, by the sprinkling of the other part of the sacrificial blood upon the people, they also were brought into the covenant as the other party thereto and were solemnly bound by it to fulfill those terms of it that applied to them. Thus by the blood the two parties, God and the nation of Israel, were united in a covenant.