Matthew 14:4

4 John had said to Herod, ‘Herodias was your brother's wife. So it is not right for you to have her as your wife.’

14:4Herodias had left Philip, her husband. Then Herod married her. God's Law said, ‘A man must not marry his brother's wife.’ See Leviticus 20:21. Herod was angry with John when he told him that.