Hebrews 3:8

do not have a stubborn heart like you did when you provoked [God] during the time you tested [His patience] in the desert,

Hebrews 3:15

As it has been said [Psa. 95:7], "Today, if you hear His [i.e., God's] voice, do not have a stubborn heart like you did when you provoked [God]."

Revelation 16:9

And people were seared by the intense heat, and they cursed the name of God, who had control over these judgments [i.e., the authority to inflict them], but they refused to repent and honor God. [See verse 2].

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 have a stubborn heart like you did when you provoked [God] during the time you tested [His patience] in the desert,
Revelation 16:9
And people were seared by the intense heat, and they cursed the name of God, who had control over these judgments [i.e., the authority to inflict them], but they refused to repent and honor God. [See verse 2].