Jamieson, Fausset and Brown on Luke 7:29-30

29-30. And all the people that heard--"on hearing (this)." These are the observations of the Evangelist, not of our Lord.

and the publicans--a striking clause.

justified God, being baptized, &c.--rather, "having been baptized." The meaning is, They acknowledged the divine wisdom of such a preparatory ministry as John's, in leading them to Him who now spake to them (see Lu 1:16, 17); whereas the Pharisees and lawyers, true to themselves in refusing the baptism of John, set at naught also the merciful design of God in the Saviour Himself, to their own destruction.