1 Corinthians 7:11-13

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.