Cross reference
1 Corinthians 7:6
6 But this I say by way of concession, not of commandment.
2 Corinthians 8:8
8 I speak not by way of commandment, but as proving through the earnestness of others the sincerity also of your love.
1 Corinthians 7:12
12 But to the rest I--not the Lord--say, if any brother has an unbelieving wife, and she is content to live with him, let him not leave her.
1 Corinthians 7:25
25 Now concerning virgins, I have no commandment from the Lord, but I give my judgment as one who has obtained mercy from the Lord to be trustworthy.
2 Corinthians 11:17
17 That which I speak, I don't speak according to the Lord, but as in foolishness, in this confidence of boasting.