Jamieson, Fausset and Brown on Luke 3:19-20

19-20. But Herod, &c.--See on Mr 6:14, &c. (Also see on Mt 3:12.)

and for all the evils which Herod had done--important fact here only mentioned, showing how thoroughgoing was the fidelity of the Baptist to his royal hearer, and how strong must have been the workings of conscience in that slave of passion when, notwithstanding such plainness, he "did many things and heard John gladly" (Mr 6:20, 26).