1 Bible Verses about Apostasy in OT

while it is said, To-day, if you will hear his voice, harden not your hearts, as in the bitter provocation. For some, when they had heard, did bitterly provoke; yet, not all that came out of Egypt by Moses. But with whom was he angry forty years? Was it not with those who sinned, whose carcasses fell in the wilderness?read more.
But to whom did he swear that they should not enter into his rest, but to those who believed not? And so we see that they could not enter in because of unbelief.