Hebrews 9:13, 18, 26

The blood of goats and bulls and the ashes of a cow are sprinkled on the people who are unclean, and this makes their bodies clean again.

This is why even the first agreement could not begin without blood to show death.

Then he would have had to suffer many times since the world was made. But Christ came only once and for all time at just the right time to take away all sin by sacrificing himself.