1 Corinthians 7:12
"But to the rest speak I, not the Lord: If any brother hath a wife that believeth not, and she be pleased to dwell with him, let him not put her away."
Cross References (ranked by relevance)
2 Corinthians 11:17
That which I speak, I speak it not after the Lord, but as it were foolishly, in this confidence of boasting.
1 Corinthians 7:6
But I speak this by permission, and not of commandment.
1 Corinthians 7:25
Now concerning virgins I have no commandment of the Lord: yet I give my judgment, as one that hath obtained mercy of the Lord to be faithful.