Read Mark 6:17 Using Other Translations
For Herod himself had sent forth and laid hold upon John, and bound him in prison for Herodias' sake, his brother Philip's wife: for he had married her.
For it was Herod who had sent and seized John and bound him in prison for the sake of Herodias, his brother Philip's wife, because he had married her.
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.