Hebrews 3:8 in the King James Version
Harden not your hearts, as in the provocation, in the day of temptation in the wilderness:
Context
7 Therefore, even as the Holy Spirit says, “Today if you will hear his voice,
8 don’t harden your hearts as in the rebellion, in the day of the trial in the wilderness,
9 where your fathers tested me and tried me, and saw my deeds for forty years.