Exodus 3:17-20

17and I have said I will bring you up out of the affliction of Egypt to the land of the Canaanites and the Hittites and the Amorites and the Perizzites and the Hivites and the Jebusites, to a land flowing with milk and honey.” ’

18Then they will heed your voice; and you shall come, you and the elders of Israel, to the king of Egypt; and you shall say to him, ‘The Lord God of the Hebrews has met with us; and now, please, let us go three days’ journey into the wilderness, that we may sacrifice to the Lord our God.’

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

20So 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.