1 Corinthians 7:6-11

But I am saying this as a concession, not as a command. I wish that all the people were as I am; but each person has his own gift from God, one of this kind and one of that. But I say to the unmarried and to the widows, [that as a practical matter] it is good if they remain [single and entirely devoted to the Lord] as I am. But if they do not have [sufficient] self-control, they should marry; for it is better to marry than to burn with passion. But to the married [believers] I give instructions—not I, but the Lord—that the wife is not to separate from her husband, (but even if she does leave him, let her remain single or else be reconciled to her husband) and that the husband should not leave his wife.