1 Corinthians 7:1-16 NIV
Now for the matters you wrote about: “It is good for a man not to have sexual relations with a woman.” But since sexual immorality is occurring, each man should have sexual relations with his own wife, and each woman with her own husband. The husband should fulfill his marital duty to his wife, and likewise the wife to her husband. The wife does not have authority over her own body but yields it to her husband. In the same way, the husband does not have authority over his own body but yields it to his wife. Do not deprive each other except perhaps by mutual consent and for a time, so that you may devote yourselves to prayer. Then come together again so that Satan will not tempt you because of your lack of self-control. I say this as a concession, not as a command. I wish that all of you were as I am. But each of you has your own gift from God; one has this gift, another has that.
Now to the unmarried and the widows I say: It is good for them to stay unmarried, as I do. But if they cannot control themselves, they should marry, for it is better to marry than to burn with passion.
To the married I give this command (not I, but the Lord): A wife must not separate from her husband. But if she does, she must remain unmarried or else be reconciled to her husband. And a husband must not divorce his wife.
To the rest I say this (I, not the Lord): If any brother has a wife who is not a believer and she is willing to live with him, he must not divorce her. And if a woman has a husband who is not a believer and he is willing to live with her, she must not divorce him. For the unbelieving husband has been sanctified through his wife, and the unbelieving wife has been sanctified through her believing husband. Otherwise your children would be unclean, but as it is, they are holy.
But if the unbeliever leaves, let it be so. The brother or the sister is not bound in such circumstances; God has called us to live in peace. How do you know, wife, whether you will save your husband? Or, how do you know, husband, whether you will save your wife?
NIV: New International Version