Exodus 9:35

Pharaoh’s heart was hardened, and he did not let the sons of Israel go, just as the Lord had spoken through Moses.

Exodus 4:21

The Lord said to Moses, “When you go back to Egypt see that you perform before Pharaoh all the wonders which I have put in your power; but I will harden his heart so that he will not let the people go.

Treasury of Scripture Knowledge

Summary

Exodus 9:35

And the heart of Pharaoh was hardened, neither would he let the children of Israel go; as the LORD had spoken by Moses.

General references

Jeremiah 34:11

Bible References

General references

But afterward they turned around and took back the male servants and the female servants whom they had set free, and brought them into subjection for male servants and for female servants.