Matthew 14:3
For Herod had seized John and bound him and put him in prison for the sake of Herodias, his brother Philip's wife. The backstory of John's imprisonment: Herod had arrested John because of Herodias, his brother Philip's wife — a marriage that John had publicly condemned as unlawful (Leviticus 18:16, 20:21). The for the sake of Herodias communicates that Herod's political power was being exercised in service of his personal relationship — a relationship John's prophetic honesty had challenged.