John’s baptism—was it from heaven, or from men?”
In this passage of story nothing is added here to what we had in the other evangelists; but only in the first verse, where we are told, I. That he was now teaching the people in the temple, and preaching the gospel. Note, Christ was a preacher of his own gospel.
Commenting on Luke 20:1-8
The baptism of John, was it from heaven, or of men? This was a new ordinance, and John must have his authority for administering it either from God, or from men; and Christ is desirous to know from which he derived it in their opinion; suggesting, that by the same authority John, his forerunner, came baptizing, he himself came preaching and working miracles; See Gill on Mat 21:25. .
baptism of John--his whole ministry and mission, of which baptism was the seal.