https://www.btstories.com/john-beheaded/

To make his wife happy, King Herod had John the Baptist arrested. John had preached against their marriage, saying, “It is a sin to marry your brother’s wife.”

Herod’s wife wanted him dead! But Herod knew that John was a righteous man. The king also feared the people, knowing that they thought he was a prophet. Besides, he enjoyed hearing John preach. So, he decided to keep the prophet in prison, instead of killing him.