And the LORD said unto Moses, When thou goest to return into Egypt, see that thou do all those wonders before Pharaoh, which I have put in thine hand: but I will harden his heart, that he shall not let the people go.
Jewish Publication Society of America Version (JPS1917) - Exodus 4:21 >And the LORD said unto Moses: 'When thou goest back into Egypt, see that thou do before Pharaoh all the wonders which I have put in thy hand; but I will harden his heart, and he will not let the people go.