if you look again you might find that Paul didnt write the books of Mark, hebrews, or proverbs, plus proverbs is old testament. ie thousand of years older than Paul himself.
Ps the only one in the references that paul wrote was corinthians, and he makes it clear when it is his own opinion ie
1 Corinthians 7:10"To the married I give this command (not I, but the Lord)...." he then changes to "To the rest I say this (I, not the Lord). so he obviously makes it clear when he is speaking and when he is relaying Gods words.
so unless the both of us believe the whole Bible is the word of God the whole argument is in vain. The whole Bible except that which Paul says is his own opinion, however i think that should also be considered as something to be followed as he speaks with wisdom and biblical common sense.