1 Corinthians 7:10

Because it is a law expressly appointed by Christ which he is about to read to them about the "not putting away a wife without fornication;" therefore he says, "Not I." True it is what was before spoken though it were not expressly stated, yet it also is His decree. But this, you see, He had delivered in express words. So that the words "I and not I" have this difference of meaning. For that you might not imagine even his own words to be human, therefore he added, "For I think that I also have the Spirit of God." Now what is that which "to the married the Lord commanded? That the wife depart not from her husband: but if she depart, let her remain unmarried, or be reconciled unto her husband." Here, seeing that both on the score of continence and other pretexts, and because of infirmities of temper, it fell out that separations took place: it were better, he says, that such things should not be at all; but however if they take place, let the wife remain with her husband, if not to cohabit with him, yet so as not to introduce any other to be her husband.