Charles Ellicott Commentary Matthew 21:28

"But what think ye? A man had two sons; and he came to the first, and said, Son, go work to-day in the vineyard." — Matthew 21:28 (ASV)

But what think ye? — The question serves to connect the parable with the previous incident and so gives point to its special primary application. In many manuscripts, the answers of the two sons are inverted, and it is accordingly the “second,” and not the first, who is said, in Matthew 21:31, to have done the will of his Father.

Go work to day in my vineyard — The parable rests on the same imagery as that of the Labourers, with some special variations. Both of those who are called to work are “sons,” and not hired labourers—i.e., there is a recognition of both Pharisees and publicans, the outwardly religious and the conspicuously irreligious, as being alike, in a sense, children of God.