“Moses went back to his father-in-law Jethro and said to him, ‘Please let me go back to my kindred in Egypt and see whether they are still living.’ Jethro said to Moses, ‘Go in peace.’ Yahweh said to Moses in Midian, ‘Go back to Egypt. All those who were seeking your life are dead.’ So Moses took his wife and his sons, put them on a donkey and went back to the land of Egypt. Moses carried the staff of God in his hand.”
Moses went to his father-in-law Jethro, and told him he was going back to Egypt. Jethro told Moses to go in peace. Notice that he is called Jethro. Yahweh had told Moses to go back to Egypt because he was no longer a wanted man. It is not clear how many years that Moses was in Midian. Anyway he took his Midian wife and children and left for Egypt with the staff of God in his hand.
“Yahweh said to Moses, ‘When you go back to Egypt, see that you perform before Pharaoh all the wonders or miracles that I have put in your power. But I will harden his heart, so that he will not let the people go. Then you shall say to Pharaoh, ‘Thus says Yahweh, Israel is my first-born son. I said to you, ‘Let my son go that he may worship me.’ But you refused to let him go. Now, I will kill your first-born son.’”
Yahweh told Moses to go to Pharaoh and do his tricks to show his power. However, he warned Moses that he was going to harden Pharaoh’s heart, so that he will not let the people go. Israel was Yahweh’s first-born son so Yahweh was going to kill Pharaoh’s first-born son. This is pretty tough language. It seems that Yahweh knows the outcome but wants Moses to still try to change Pharaoh’s mind.