Matthew 19:6-9

6Therefore they are no more two, but one flesh. Therefore what God hath joined together, let not man put asunder. 7They say to him, Why did Moses then command to give a writing of divorcement, and to put her away? 8He saith to them, Moses because of the hardness of your hearts permitted you to put away your wives: but from the beginning it was not so. 9And I say to you, Whoever shall put away his wife, except for immorality, and shall marry another, committeth adultery: and whoever marrieth her who is put away committeth adultery.