Exodus 12:27-29

Young's Literal Translation

²⁷ that ye have said, A sacrifice of passover it [is] to Jehovah, who passed over the houses of the sons of Israel in Egypt, in His smiting the Egyptians, and our houses He delivered.'

²⁸ And the people bow and do obeisance, and the sons of Israel go and do as Jehovah commanded Moses and Aaron; so have they done.

²⁹ And it cometh to pass, at midnight, that Jehovah hath smitten every first-born in the land of Egypt, from the first-born of Pharaoh who is sitting on his throne, unto the first-born of the captive who [is] in the prison-house, and every first-born of beasts.