Matthew 5:31-32 - The Sermon On The Mount: Divorce
31 It was also said [Deut. 24:1-3], 'Whoever divorces his wife, let it be done with a [legally binding] divorce decree, which he must give her.' 32 But I say to you, every person who divorces his wife makes her become sexually unfaithful to him [i.e., since she will probably marry someone else], unless the reason for the divorce is that she had [already] become sexually unfaithful to him. And whoever marries a woman who has been divorced commits sexual sin with her [i.e., because she is still rightfully married to her first husband].