Exodus 12:28-31

Then Bnei-Yisrael went and did it. They did just as ADONAI had commanded Moses and Aaron. So it came about at midnight that ADONAI struck down all the firstborn in the land of Egypt, from the firstborn of Pharaoh sitting on his throne to the firstborn of the captive who was in the dungeon, and all the firstborn cattle. Then Pharaoh rose up in the night, he and all his servants and all the Egyptians, and there was loud wailing in Egypt. For there was not a house where someone was not dead. So he called for Moses and Aaron at night and said, “Rise up, go out from my people, both you and Bnei-Yisrael, go, serve ADONAI as you have said.