Hebrews 3:15-19

while it is said, “Today if you hear His voice, Do not harden your hearts, as when they provoked Me.”

For who provoked Him when they had heard? Indeed, did not all those who came out of Egypt led by Moses?

And with whom was He angry for forty years? Was it not with those who sinned, whose dead bodies fell in the wilderness?

And to whom did He swear that they would not enter His rest, but to those who were disobedient?

And so we see that they were not able to enter because of unbelief.