Exodus 9:35

and the heart of Pharaoh is strong, and he hath not sent the sons of Israel away, as Jehovah hath spoken by the hand of Moses.

Exodus 4:21

And Jehovah saith unto Moses, 'In thy going to turn back to Egypt, see -- all the wonders which I have put in thy hand -- that thou hast done them before Pharaoh, and I -- I strengthen his heart, and he doth not send the people away;

Treasury of Scripture Knowledge

Summary

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

Bible References

General references

Jeremiah 34:11
and they turn afterwards, and cause the men-servants and the maid-servants to return, whom they had sent forth free, and they subdue them for men-servants and for maid-servants.