“On that night I will go through the land of Egypt, killing every first-born male, both human and animal, and punishing all the gods of Egypt. I am the Lord.
When the king of Egypt was stubborn and refused to let us go, the Lord killed every first-born male in the land of Egypt, both human and animal. That is why we sacrifice every first-born male animal to the Lord, but buy back our first-born sons.
It was faith that made him establish the Passover and order the blood to be sprinkled on the doors, so that the Angel of Death would not kill the first-born sons of the Israelites.