Moses took half of the blood. The blood, which symbolised the life of the victim, was the essential part of every sacrifice, and was usually poured over the altar, or at any rate sprinkled upon it, as the very crowning act of offering.
(See Le Exodus 1:5; Exodus 3:8; etc.) On this occasion Moses retained half of the blood, and put it in basins, for the purpose of so uniting all the people in the sacrifice, and thereby the more solemnly pledging them to the covenant, which the sacrifice at once consecrated and consummated.
(See Hebrews 9:18-20.) The other half of the blood was, according to the usual practice, sprinkled upon the altar.