Parallel
Exodus 4:21
Brenton's English Septuagint · Berean Standard Bible
And the Lord said to Moses, When thou goest and returnest to Egypt, see—all the miracles I have charged thee with, thou shalt work before Pharao: and I will harden his heart, and he shall certainly not send away the people.
The LORD instructed Moses, “When you go back to Egypt, see that you perform before Pharaoh all the wonders that I have put within your power. But I will harden (note: Or stiffen or strengthen) his heart so that he will not let the people go.