"The apostle says, “All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: that the man of God may be perfect, thoroughly furnished unto all good works.” [ 2 Timothy 3:16, 17 .] The Bible is its own expositor. One passage will prove to be a key that will unlock other passages, and in this way light will be shed upon the hidden meaning of the word. By comparing different texts treating on the same subject, viewing their bearing on every side, the true meaning of the Scriptures will be made evident. CE 85.1"
"All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:"
EGW directly quotes 2 Timothy 3:16 and explicitly connects it to the value of scripture.