"The importance of seeking a thorough knowledge of the Scriptures can hardly be estimated. “Given by inspiration of God,” able to make us “wise unto salvation,” rendering the man of God “perfect, throughly furnished unto all good works” ( 2 Timothy 3:15-17 ), the Bible has the highest claim to our reverent attention. We should not be satisfied with a superficial knowledge, but should seek to learn the full meaning of the words of truth, to drink deep of the spirit of the Holy Oracles. CT 139.2"
"And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus. 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, throughly furnished unto all good works."
Ellen White directly references 2 Timothy 3:15-17 in this passage.