I Corinthians 7:11-13

But even if she does depart, let her remain unmarried or be reconciled to her husband. And a husband is not to divorce his wife. But to the rest I, not the Lord, say: If any brother has a wife who does not believe, and she is willing to live with him, let him not divorce her. And a woman who has a husband who does not believe, if he is willing to live with her, let her not divorce him.