Mark 6:18

6:18 For John had repeatedly told Herod, “It is not lawful for you to have your brother’s wife.”

Mark 10:2

10:2 Then some Pharisees came, and to test him they asked, “Is it lawful for a man to divorce his wife?”

Mark 10:11

10:11 So he told them, “Whoever divorces his wife and marries another commits adultery against her.

Mark 12:20

12:20 There were seven brothers. The first one married, and when he died he had no children.