Matthew 21:32

For John came unto you in a way of righteousness
He had a commission from God; he was no impostor; the doctrine he taught was true, and which he faithfully delivered; his life and conversation were unblamable; there was nothing in his credentials, ministry, and conduct, that could justly be found fault with:

and ye believed him not;
to be the forerunner of the Messiah, or the Elias that was to come; nor attended to the doctrine of repentance preached by him, nor were subject to the ordinance of baptism he administered; nor gave any assent, or credit, to the Messiah he so manifestly pointed out:

but the publicans and harlots believed him;
what he said concerning the wrath to come, and the miserable state and danger they were in; and they repented of their sins, and confessed them, and were baptized of him in Jordan; believing the testimony he gave of Jesus of Nazareth being the Messiah, and Son of God:

and ye, when ye had seen it;
the repentance and faith of these persons, and what a wonderful reformation was wrought in them,

repented not afterwards;
of their disobedience, impenitence, and unbelief, after they had seen the effects of John's ministry on these very profligate sinners, and after, the death of John; who, by his constancy, zeal, and faithfulness, had shown himself to be a true, and upright minister of the word; and afterwards under the ministry of Christ, and his apostles, by, whom the same doctrines were preached, and the same ordinances administered,

that ye might believe him;
the testimony he has left behind him concerning the Messiah.