Well, it depends on what someone means by sola scriptura. I think usually people mean the Bible has all we need to know and do, in order to be saved and live for God and be Raptured and do well in judgment and then share eternity with God and one another as God's own family.
And, yes, there is scripture which says not to add to what God has written to us. Deuteronomy 4:2 says what I think means this. Also, in Revelation we are told not to add to the Book of Revelation, if I understand this scripture right > Revelations 22:18. But ones understand that if we are not to add to the Book of Revelation, it makes sense that God does not want us to add to anything else of His word.
In any case, we do need all which God means by the Bible; so we need to make sure we study and know and live all which the Bible means. But this comes mainly by trusting in Christ > Ephesians 1:12, and submitting to all which God pleases to do with us > Proverbs 3:5-6, James 4:7, Colossians 3:15, Hebrews 12:4-11, 1 John 4:17-18.
But included in what the Bible says is that we the children of God are an "epistle of Christ written in our hearts", in 2 Corinthians 3:1-3. We, not a paper book, are the message of God, I consider this means. We are the living meaning, the love meaning which words are not enough to tell, though we need to grow and mature more and get more correction of His love's perfection > 1 John 4:17.
And, talking about love, we have >
"Now hope does not disappoint, because the love of God has been poured out in our hearts by the Holy Spirit who was given to us." (Romans 5:5)
So, we children of God have God's own love being shared with us "in our hearts" by the Holy Spirit. This is not just scripture. So, there is more than scripture > there is all which God Himself does in us and our lives and ministry. And God does all He knows His word means >
"'So shall My word be that goes forth from My mouth;
. It shall not return to Me void,
. But it shall accomplish what I please,
. And it shall prosper in the thing for which I sent it.'"
. . . . . . . . . . . . . . . . . . . . (Isaiah 55:11)
So it is not enough to have the scriptures, but we also need how the Holy Spirit in us and our lives produces all which God Himself understands His word to mean. And we discover this by submitting to God (James 4:7, Proverbs 3:5-6), actively seeking His correction (Hebrews 12:4-11), and growing in His love so "that we may have boldness in the day of judgment; because as He is, so are we in this world." (in 1 John 4:17-18)
So, we need how God perfects us in His love, "that we may have boldness in the day of judgment; because as He is, so are we in this world." This is what God wants, and Isaiah 55:11 guarantees that this word of God will accomplish what He pleases.
So, yes we do need the holy scriptures, but we also need how God does all He means by His word, with us.
And if God's grace does in us what the Bible says, this is enough. Even so, there are people and things which God uses which are not in the Bible and not specified in detail in God's word.
But are there traditions and messages which are not in the Bible, but we need them?
I believe that the Bible has what we need, in order to be saved and then conformed into the image of Jesus and in order for us to love the way God wants. But in our everyday lives there are specific people and activities which God wants to share with us. So, I believe these can be essential if God wants them.
If He arranged that you heard a certain preacher in order to get saved, that was essential. If He provides us with a certain church which He uses to mature us in Jesus, this is essential. And there are trials and problems which can be essential.
So, I think the practical thing to do is to simply submit to God and discover all He does with us. All His grace does in us is essential, I would say.
And I think the Bible gives us enough. No more is necessary, in general. But, like I say, if there are certain things God wants for an individual, these things can be essential. And what the Holy Spirit has us saying in prayer is, I think, the word of God, if it is what God has us saying. And our prayers might not have actual quotes of the Bible.
So, I agree with the basic idea of sola scriptura, I think, but I understand there is all which God Himself shares with us, and this is all essential
