Another passage generally used to try to prove the Protestant doctrine of sola-Scriptura is 1 Corinthians 4:6 – “I have applied all this to myself and Apol′los for your benefit, brethren, that you may learn by us not to go beyond what is written, that none of you may be puffed up in favor of one against another.” 

That passage leads some to conclusions such as:

“No one has the right to go beyond what is written in Scripture.  Scripture warns us not to exceed what is written.”  (James McCarthy, “The Gospel According to Rome” – an anti-Catholic work)

And:

Sola scriptura is all-but-explicitly indicated in 1 Corinthians 4:6, where Paul warns not to “go beyond what is written.”

https://www.gotquestions.org/sola-scriptura.html

Using this passage to prove sola-Scripture is problematic. Sola-Scriptura in general refers to a belief that Scripture is the only infallible authority for the Christian faith, and that all teaching must conform to Scripture as the final authority. But this passage in context isn’t talking about doctrine, or teaching the faith.  It’s talking about who is saved.  The passage in context – “This is how one should regard us, as servants of Christ and stewards of the mysteries of God.  Moreover it is required of stewards that they be found trustworthy.  But with me it is a very small thing that I should be judged by you or by any human court.  I do not even judge myself.  I am not aware of anything against myself, but I am not thereby acquitted.  It is the Lord who judges me.  Therefore do not pronounce judgment before the time, before the Lord comes, who will bring to light the things now hidden in darkness and will disclose the purposes of the heart.  Then every man will receive his commendation from God.  I have applied all this to myself and Apol′los for your benefit, brethren, that you may learn by us not to go beyond what is written, that none of you may be puffed up in favor of one against another.”  (1 Corinthians 4:1-6)

Applying this passage to accurately determine correct doctrine simply isn’t the context.  Evidently the Corinthians were having some “ego” issues about being saved, and Paul tells them he’s applying his warning to himself and Apollos so they can learn from them about not pronouncing judgement before the time when Christ comes to judge. So what does that have to do with not going beyond what is written?  The other problem with trying to prove sola-Scriptura from this passage is it doesn’t reference Scripture at all.  In other passages where the Bible speaks about Scripture, it uses the Greek word graphē to denote the “writings.”  Paul uses the term graphē consistently when he’s referring to Sacred Scripture (Romans 1:2, Romans 4:3, Romans 9:17, Romans 10:11, Romans 11:2, Romans 15:4, 1 Corinthians 15:3, 1 Corinthians 15:4, Galatians 3:8, Galatians 3:22, Galatians 4:30, 1 Timothy 5:18, 2 Timothy 3:16).  In this passage, the term graphē is most notably missing, which is why the word “Scripture” is not present in the translation.

Sometimes we can be so fixated on what we think we know, we can miss the point.  Why did St. Paul not use the word Scripture here?  Some simply conclude he has to be speaking about Scripture without considering another alternative.

Given that the context is who is and who is not saved, there is another book that better fits the context, known in Scripture as the Lamb’s book of life, where the names of all of those who are saved have been written:

Philippians 4:2-3 I entreat Eu-o′dia and I entreat Syn′tyche to agree in the Lord.  And I ask you also, true yokefellow, help these women, for they have labored side by side with me in the gospel together with Clement and the rest of my fellow workers, whose names are in the book of life.

Revelation 3:5 He who conquers shall be clad thus in white garments, and I will not blot his name out of the book of life; I will confess his name before my Father and before his angels.

Revelation 13:7-8 Also it was allowed to make war on the saints and to conquer them.  And authority was given it over every tribe and people and tongue and nation, and all who dwell on earth will worship it, every one whose name has not been written before the foundation of the world in the book of life of the Lamb that was slain.

Revelation 17:8 The beast that you saw was, and is not, and is to ascend from the bottomless pit and go to perdition; and the dwellers on earth whose names have not been written in the book of life from the foundation of the world, will marvel to behold the beast, because it was and is not and is to come.

Revelation 21:27 But nothing unclean shall enter it, nor any one who practices abomination or falsehood, but only those who are written in the Lamb’s book of life.

Revelation 20:11-15 Then I saw a great white throne and him who sat upon it; from his presence earth and sky fled away, and no place was found for them.  And I saw the dead, great and small, standing before the throne, and books were opened.  Also another book was opened, which is the book of life.  And the dead were judged by what was written in the books, by what they had done.  And the sea gave up the dead in it, Death and Hades gave up the dead in them, and all were judged by what they had done.  Then Death and Hades were thrown into the lake of fire.  This is the second death, the lake of fire; and if any one’s name was not found written in the book of life, he was thrown into the lake of fire.

St. Paul warns the Corinthians in 1 Corinthians 4:5 “Therefore do not pronounce judgment before the time, before the Lord comes, who will bring to light the things now hidden in darkness and will disclose the purposes of the heart.  Then every man will receive his commendation from God.”  This has a direct tie to the passage from Revelation 20:11-15 which speaks to the judgment at the end of time. Two books are open. One is the book of life, and those whose names are written in this book are saved. The other is a book that contains the record of all our deeds by which we will be judged.  When St. Paul warns them in verse 6 to therefore “do not go beyond what is written,” he confirms that it will be Christ’s place to judge who and who is not saved, not theirs. That judgment will be based upon what is written in these books that will be opened at the end of time.

Given that the context of the passage is about who is saved and the fact that St. Paul does not reference the graphē (Scripture) in the passage, it is much more fitting with the context of the passage to understand he’s referring to names being written in the Lamb’s book of life, and the record of our deeds.  What is certain however is the context has nothing to do with determining correct doctrine or teaching the faith, so in no way supports a view of Scripture alone as being the sole rule of faith.