“Now the Lord said to Moses, “One more plague I will bring on Pharaoh and on Egypt; ‘About midnight I am going out into the midst of Egypt, and all the firstborn in the land of Egypt shall die, from the firstborn of the Pharaoh who sits on his throne, even to the firstborn of the slave girl who is behind the millstones; all the firstborn of the cattle as well. Moreover, there shall be a great cry in all the land of Egypt, such as there has not been before and such as shall never be again. Exodus 11
That was when God sent his angel to slay all the first-born in Egypt – the last plague that convinced Pharaoh to let the Hebrew children go.
The thing that distinguished the Hebrew children from the Egyptians on the night the angel passed over was the shed blood of a lamb on the door posts. Our only hope is in the blood of the Lamb.
On Friday we will remember the sacrifice Jesus made on the Cross for us. He shed His own blood so that we might be forgiven and made new.