Hebrews 3:8

Do not harden your hearts as your forefathers provoked me by doing, As in that time of trial in the desert,

Hebrews 3:15

So while we can still speak of Today, if you hear him speak, do not harden your hearts, as they provoked him by doing.

Revelation 16:9

and they were dreadfully scorched, but they reviled the name of God who had control of these plagues, and would not repent and give him glory.

Treasury of Scripture Knowledge

Summary

But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them; as the LORD had said.

Bible References

He hardened

Hebrews 3:8
Do not harden your hearts as your forefathers provoked me by doing, As in that time of trial in the desert,
Revelation 16:9
and they were dreadfully scorched, but they reviled the name of God who had control of these plagues, and would not repent and give him glory.