A.T. Robertson Commentary Matthew 21:29

"And he answered and said, I will not: but afterward he repented himself, and went." — Matthew 21:29 (ASV)

I will not (ου θελω). So many old manuscripts, though the Vatican manuscript (B) has the order of the two sons reversed. Logically the "I, sir" (εγω, κυριε) suits better for the second son (verse 30) with a reference to the blunt refusal of the first. So also the manuscripts differ in verse 31 between the first (ο πρωτος) and the last (ο υστερος or εσχατος). But the one who actually did the will of the father is the one who

repented and went (μεταμεληθεις απηλθεν). This word really means "repent," to be sorry afterwards, and must be sharply distinguished from the word μετανοεω used 34 times in the N.T. as in Mt 3:2 and μετανοια used 24 times as in Mt 3:8. The verb μεταμελομα occurs in the N.T. only five times (Matthew 21:29,32; 27:3; 2 Corinthians 7:8; Hebrews 7:21 from Ps 109:4). Paul distinguishes sharply between mere sorrow and the act "repentance" which he calls μετανοιαν (2 Corinthians 7:9). In the case of Judas (Matthew 27:3) it was mere remorse. Here the boy got sorry for his stubborn refusal to obey his father and went and obeyed. Godly sorrow leads to repentance (μετανοιαν), but mere sorrow is not repentance.