Romans 2:5

But your stubbornness and refusal to repent are storing up wrath [i.e., punishment] for yourselves, [to be experienced] on the Day of Wrath [i.e., the day of judgment] when God's just judgment will be revealed.

Hebrews 3:8-9

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

Hebrews 3:13

But [instead], encourage one another each day, as long as it is [still] called "Today," so that none of you becomes stubborn [as a result] of the deceitfulness of sin.

Hebrews 3:15-19

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]."

Hebrews 12:25

Pay careful attention so that you do not refuse [to hear] God when He speaks to you. [See verse 9]. For if those people [i.e., the Israelites] did not escape [judgment] when they refused [to hear] Him who warned them on earth [i.e., God speaking through Moses at Mount Sinai], how much less [likely] will we escape [judgment] if we reject Him who warns from heaven [i.e., Christ]?

Jude 1:5

But, I want to remind you, [even] though you already know the stories about how the Lord delivered His people from Egyptian [bondage], and then [later] destroyed those who did not believe [in Him].

Acts 19:9

But some became stubborn and refused to obey [the message], saying false things about "the Way" [Note: This was a term used to designate the early church] in front of the large crowds. So, Paul left [the synagogue] and took the disciples and began holding discussions every day at Tyrannus' school [house].

Treasury of Scripture Knowledge

Summary

Harden not your heart, as in the provocation, and as in the day of temptation in the wilderness:

Bible References

Harden

Acts 19:9
But some became stubborn and refused to obey [the message], saying false things about "the Way" [Note: This was a term used to designate the early church] in front of the large crowds. So, Paul left [the synagogue] and took the disciples and began holding discussions every day at Tyrannus' school [house].
Romans 2:5
But your stubbornness and refusal to repent are storing up wrath [i.e., punishment] for yourselves, [to be experienced] on the Day of Wrath [i.e., the day of judgment] when God's just judgment will be revealed.
Hebrews 3:13
But [instead], encourage one another each day, as long as it is [still] called "Today," so that none of you becomes stubborn [as a result] of the deceitfulness of sin.
Hebrews 12:25
Pay careful attention so that you do not refuse [to hear] God when He speaks to you. [See verse 9]. For if those people [i.e., the Israelites] did not escape [judgment] when they refused [to hear] Him who warned them on earth [i.e., God speaking through Moses at Mount Sinai], how much less [likely] will we escape [judgment] if we reject Him who warns from heaven [i.e., Christ]?

In the

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,
Jude 1:5
But, I want to remind you, [even] though you already know the stories about how the Lord delivered His people from Egyptian [bondage], and then [later] destroyed those who did not believe [in Him].