The Apostolic Teaching is not confined to Scripture, WCH, and they were teaching this before the NT was written. However, there are references to this teaching in the Scripture.
Acts 17:29-31
29 Being then God’s offspring, we ought not to think that the Deity is like gold, or silver, or stone, a representation by the art and imagination of man. 30 The times of ignorance God overlooked, but** now he commands all men everywhere to repent**, 31 because he has fixed a day on which he will judge the world in righteousness by a man whom he has appointed, and of this he has given assurance to all men by raising him from the dead."
Why would the He command those to repent that did not have the ability to do so?
Rom 11:32
2 For God has consigned all men to disobedience, that he may have mercy upon all.
Some men dont’ want His mercy, and don’t receive it.
Luke 7:28-30
28 I tell you, among those born of women none is greater than John; yet he who is least in the kingdom of God is greater than he." 29(When they heard this all the people and the tax collectors justified God, having been baptized with the baptism of John; 30 but the Pharisees and the lawyers rejected the purpose of God for themselves, not having been baptized by him.)
If God did not intend for the Pharisees to repent and believe in the Gospel (did not give them sufficient grace to repent) then how could they 'reject the purpose of God for themselves" by not believing?