Jesus didn't even claim that ALL he said was from God.......and neither has any figure in Biblical history. But it's clearly understood that Paul gives instruction from God. There are many Biblical accounts of God speaking audibly to Paul, as to a prophet. Many accounts of Paul performing miracles, again, like a prophet. And many accounts of Paul seeing visions, once again, like a prophet. And there are many instances in Paul's epistles in which he states "Not the Lord says this, but I" in which he's clearly implying that everything in that epistle is to be taken as revelation from God unless he specifically states otherwise.