Hebrews 3:19

19Andκαὶwe seeβλέπομενthatὅτιnotοὐκthey were ableἠδυνήθησανto enter inεἰσελθεῖνbecause ofδι’unbeliefἀπιστίαν.

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