Luke 20:4

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 Matthew 21:25).