17 For Herod had sent soldiers to arrest and imprison John as a favor to Herodias. She had been his brother Philip's wife, but Herod had married her. 18 John had been telling Herod, "It is against God's law for you to marry your brother's wife." 19 So Herodias bore a grudge against John and wanted to kill him. But without Herod's approval she was powerless,
Matthew Henry's Commentary on Mark 6:17-19
Commentary on Mark 6:14-29
(Read Mark 6:14-29)
Herod feared John while he lived, and feared him still more when he was dead. Herod did many of those things which John in his preaching taught him; but it is not enough to do many things, we must have respect to all the commandments. Herod respected John, till he touched him in his Herodias. Thus many love good preaching, if it keep far away from their beloved sin. But it is better that sinners persecute ministers now for faithfulness, than curse them eternally for unfaithfulness. The ways of God are unsearchable; but we may be sure he never can be at a loss to repay his servants for what they endure or lose for his sake. Death could not come so as to surprise this holy man; and the triumph of the wicked was short.