"was John's baptism of Heavenly or of human origin?"

It is about John's baptism – was it of divine or of human origin?"

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.

baptism of John--his whole ministry and mission, of which baptism was the seal.