The second. He typifies the Pharisees, the scrupulous observers of outward form, while neglectful of the weightier matters—judgment, mercy, and faith (Matthew 23:23). I go, sir, ἐγω Ì κυ ìριε: Eo, domine.
This son is outwardly respectful and dutiful; his answer is in marked contrast to the rough "I will not" of his brother. He professes zeal for the Law, and ready obedience. And went not. Such men did no real work for God, honouring him with their lips and outward observances, while their heart was far from him, and their morality was unprincipled and impure.