Exodus 4:18-23

18And Moses went and returned to Jethro his father-in-law, and said to him, Let me go, I pray thee, and return to my brethren who are in Egypt, that I may see whether they are yet alive. And Jethro said to Moses, Go in peace.

19And Jehovah said to Moses in Midian, Go, return to Egypt; for all the men are dead who sought thy life.

20And Moses took his wife and his sons, and set them riding upon an ass, and he returned to the land of Egypt. And Moses took the staff of 1God in his hand.

21And Jehovah said to Moses, When thou goest to return to Egypt, see that thou do all the wonders before Pharaoh that I have put in thy hand. And I will harden his heart, that he shall not let the people go.

22And thou shalt say to Pharaoh, Thus saith Jehovah: Israel is my son, my firstborn.

23And I say to thee, Let my son go, that he may serve me. And if thou refuse to let him go, behold, I will kill thy son, thy firstborn.