Hebrews 3:7-10, 16-19

Wherefore (as the Holy Ghost saith, To day if ye will hear his voice, Harden not your hearts, as in the provocation, In the day of temptation in the wilderness: When your fathers tempted me, proved me, And saw my works forty years. Wherefore I was grieved with that generation, And said, They do alway err in their heart; And they have not known my ways.

For some, when they had heard, did provoke: howbeit not all that came out of Egypt by Moses. But with whom was he grieved forty years? was it not with them that had sinned, whose carcases fell in the wilderness? And to whom sware he that they should not enter into his rest, but to them that believed not? So we see that they could not enter in because of unbelief.