Charles Ellicott Commentary Luke 3:19-20

"but Herod the tetrarch, being reproved by him for Herodias his brother`s wife, and for all the evil things which Herod had done, added this also to them all, that he shut up John in prison." — Luke 3:19-20 (ASV)

But Herod the tetrarch.—See Notes on Matthew 14:3-5. Luke's anticipation of the close of the Baptist’s history supplies a curious instance of an arrangement which was obviously deliberate. It seemed to him better to complete the account of the Baptist’s ministry here than to bring in the account of the imprisonment as an episode later on. It coincides in part with John's arrangement (John 3:24).

For all the evils which Herod had done.—The marriage with Herodias is conspicuous as the Tetrarch’s one great crime; but the sensual, crafty character of the man, with his fox-like nature (Luke 13:32), must have made any preaching of righteousness, temperance, and judgment to come as much a personal rebuke to him as it was to Felix (Acts 24:25), and caused him also to tremble.