The Gospel According to Mark 10:2-12
At that time, the Pharisees came up to Jesus and in order to test him, asked, "Is it lawful for a man to divorce his wife?" He answered them, "What did Moses command you?" They said, "Moses allowed a man to write a certificate of divorce, and to put her away." But Jesus said to them, "For your hardness of heart he wrote you this commandment. But from the beginning of creation, 'God made them male and female. For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh.' So they are no longer two but one flesh. What therefore God has joined together, let not man put asunder." And in the house the disciples asked him again about this matter. And he said to them, "Whoever divorces his wife and marries another commits adultery against her; and if she divorces her husband and marries another, she commits adultery."