I Corinthians 14:21 In the Law it is written, "By people of strange tongues and by the lips of foreigners will I speak to this people, and even then they will not listen to me, says the Lord."
In other words, Paul does not quote God except for the three introductory verses in Acts 9. John quotes throughout his Revelation, but Paul doesn't.
That is what we mean when we say that, for example, Matthew, Mark, Luke and John quote God Alighty. Paul doesn't except for three introductory verses in Acts 9. We hold the direct quotes from God to be superior to any man's. That includes both Peter and Paul.
You know that isn't true, you've been given the scripture before. Stop with the feigned ignorance. It doesn't become you.
I just got started looking up the verses where Paul quotes from God and where he speaks as from God himself. Just read Romans to start with. Good grief! He begins the whole book starting with his authority to speak the gospel.
Romans 1
1Paul, a servant of Christ Jesus, called to be an apostle and set apart for the gospel of God— 2the gospel he promised beforehand through his prophets in the Holy Scriptures 3regarding his Son, who as to his human nature was a descendant of David, 4and who through the Spirit of holiness was declared with power to be the Son of God by his resurrection from the dead: Jesus Christ our Lord. 5Through him and for his name's sake, we received grace and apostleship to call people from among all the Gentiles to the obedience that comes from faith. 6And you also are among those who are called to belong to Jesus Christ. 7To all in Rome who are loved by God and called to be saints: Grace and peace to you from God our Father and from the Lord Jesus Christ.
Skip over to chapter 9 and we read:
1I speak the truth in Christ—I am not lying, my conscience confirms it in the Holy Spirit—
And that was just one book and a few verses in it. I think Mark gives us "busy-work" sometimes thinking he can get us frustrated and let him get away with saying whatever he wants without challenge. Wont work! Still like ya!
Well, who do you think is speaking in Isaiah 28:11??
Fill in the blank. Who is speaking in Isaiah 28:17? ___________________
I picked a verse, one out of many that could be adduced, (many examples have already been provided by others here) that meets your criteria:
1. Paul quoting God.
2. "in support of his writings".
1. In I Corinthians 14:21 Paul quotes from Isaiah 28:11 to prove a point. That satisfies your criteria, "in support of his writings"
2. Paul substitutes "says the Lord" in his quotation, which is incoherent without the assumption that the Scripture he quoted was God speaking.
3. It necessarily follows that when he quoted Isaiah 28:11 he was quoting God.
Conclusion: Paul is quoting God when he quotes Isaiah 28:11; as he makes unmistakably clear with, "... says the Lord"
Those words constitute, to use your terminology, "direct quotes from God".
Cordially,