Matthew 14:3-5

14:3 For Herod had arrested John, bound him, and put him in prison on account of Herodias, his brother Philip’s wife, 14:4 because John had repeatedly told him, “It is not lawful for you to have her.” 14:5 Although Herod wanted to kill John, he feared the crowd because they accepted John as a prophet.

Matthew 14:10

14:10 So he sent and had John beheaded in the prison.