"***** The worker for God should be prepared to put forth the highest mental and moral energies with which nature, cultivation, and the grace of God have endowed him; but his success will be proportionate to the degree of consecration and self-sacrifice in which the work is done, rather than to either natural or acquired endowments. The most earnest and continued efforts to acquire qualifications for usefulness are necessary; but unless God works with the human effort, nothing can be accomplished. Christ says, “Without Me ye can do nothing.” [ John 15:5 .] Divine grace is the great element of saving power; without it all human efforts are unavailing.— Testimonies for the Church 5:583 . GW 80.3"
"I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing."
Ellen White directly references John 15:5 in this passage.