Whether of them (the) twain! Christ forces from the unwilling hearers an answer which, at the moment, they do not see will condemn themselves. Unaccustomed to be criticized and put to the question, wrapped in a self-complacent righteousness, which was generally undisturbed, they missed the bearing of the parable on their own case, and answered without hesitation, as any unprejudiced person would have decided.
The first; i.e. the son who first refused, but afterwards repented and went. Verily I say unto you. Jesus drives the moral home to the hearts of these hypocrites. The publicans and the harlots. He specifies these excommunicated sinners as examples of those represented by the first son.
Go into the kingdom of God before you; προα ìγουσιν ὑμας: are preceding you. This was the fact which Jesus saw and declared, he does not cut off all hope that the Pharisees might follow, if they willed to do so; he only shows that they have lost the position which they ought to have occupied, and that those whom they despised and spurned have accepted the offered salvation, and shall have their reward.
We must remark that the Lord has no censure for those who sometime were disobedient, but afterwards repented; his rebuke falls on the professors and self-righteous, who ought to have been leaders and guides, and were in truth impious and irreligious.