Hebrews 3:17

15While it is said, To day if ye will hear his voice, harden not your hearts, as in the provocation.

16For some, when they had heard, did provoke: howbeit not all that came out of Egypt by Moses.

17But with whom was he grieved forty years? was it not with them that had sinned, whose carcases fell in the wilderness?

18And to whom sware he that they should not enter into his rest, but to them that believed not?

19So we see that they could not enter in because of unbelief.