See the notes at Matthew 14:1-13. “Added this above all.” To all his former crimes he added this; not implying that this was the “worst” of his acts, but that this was “one” of his deeds, of like character as the others. The event here mentioned did not take place until some time after this, but it is mentioned here to show what was the end of John’s preaching, or to “fill out” the account concerning him.
Related Commentaries of Luke 3:19
Luke 3:19-20
19 But Herod the tetrarch, being reproved by him for Herodias his brother Philip's wife, and for all the evils which Herod had done,
20 Added yet this above all, that he shut up John in prison.