Exodus 3:19-21 New King James Version (NKJV)

19. But I am sure that the king of Egypt will not let you go, no, not even by a mighty hand.

20. So I will stretch out My hand and strike Egypt with all My wonders which I will do in its midst; and after that he will let you go.

21. And I will give this people favor in the sight of the Egyptians; and it shall be, when you go, that you shall not go empty-handed.

Exodus 3