Exodus 11:10

4 And Moses said, Thus saith Jehovah, About midnight will I go out into the midst of Egypt:

5 and all the first-born in the land of Egypt shall die, from the first-born of Pharaoh that sitteth upon his throne, even unto the first-born of the maid-servant that is behind the mill; and all the first-born of cattle.

6 And there shall be a great cry throughout all the land of Egypt, such as there hath not been, nor shall be any more.

7 But against any of the children of Israel shall not a dog move his tongue, against man or beast: that ye may know how that Jehovah doth make a distinction between the Egyptians and Israel.

8 And all these thy servants shall come down unto me, and bow down themselves unto me, saying, Get thee out, and all the people that follow thee: and after that I will go out. And he went out from Pharaoh in hot anger.

9 And Jehovah said unto Moses, Pharaoh will not hearken unto you; that my wonders may be multiplied in the land of Egypt.

10 And Moses and Aaron did all these wonders before Pharaoh: and Jehovah hardened Pharaoh`s heart, and he did not let the children of Israel go out of his land.