1 Bible Verses about Apostasy in OT

seeing that the warning still comes to us, "To-day, if you hear His voice, do not harden your hearts as your forefathers did in the time of the provocation." For who were they that heard, and yet provoked God? Was it not the whole of the people who had come out of Egypt under the leadership of Moses? And with whom was God so greatly grieved for forty years? Was it not with those who had sinned, and whose dead bodies fell in the Desert?read more.
And to whom did He swear that they should not be admitted to His rest, if it was not to those who were disobedient? And so we see that it was owing to lack of faith that they could not be admitted.