Exodus 11:4-6

11:4 Moses said, “Thus says the Lord: ‘About midnight I will go throughout Egypt, 11:5 and all the firstborn in the land of Egypt will die, from the firstborn son of Pharaoh who sits on his throne, to the firstborn son of the slave girl who is at her hand mill, and all the firstborn of the cattle. 11:6 There will be a great cry throughout the whole land of Egypt, such as there has never been, nor ever will be again.

Exodus 12:29-30

The Deliverance from Egypt

12:29 It happened at midnight – the Lord attacked all the firstborn in the land of Egypt, from the firstborn of Pharaoh who sat on his throne to the firstborn of the captive who was in the prison, and all the firstborn of the cattle. 12:30 Pharaoh got up in the night, along with all his servants and all Egypt, and there was a great cry in Egypt, for there was no house in which there was not someone dead.