1 Corinthians 7:11-13

(but if she does leave, she must remain unmarried, or else be reconciled to her husband), and that the husband should not divorce his wife. But to the rest I say, not the Lord, that if any brother has a wife who is an unbeliever, and she consents to live with him, he must not divorce her. And a woman who has an unbelieving husband, and he consents to live with her, she must not send her husband away.