"There is no need for weakness in the ministry. The message of truth that we bear is all-powerful. But many ministers do not put their minds to the task of studying the deep things of God. If these would have power in their service, obtaining an experience that will enable them to help others, they must overcome their indolent habits of thought. Let ministers put the whole heart into the task of searching the Scriptures, and a new power will come to them. A divine element unites with human effort when the soul reaches out after God; and the yearning heart may say, “My soul, wait thou only upon God; for my expectation is from Him.” [ Psalm 62:5 .] GW 98.3"
"My soul, wait thou only upon God; for my expectation is from him."
Ellen White directly references Psalms 62:5 in this passage.