This refers to the blood of the lambs that the Levites killed. Here "received from the hand of the Levites" is a metonym for the Levites giving the blood to the priests. AT: "the blood that they received from the Levites" or "the lambs' blood that the Levites gave to them" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-metonymy]])