"Ministers of Christ, link yourselves up with this class. Pass them not by as hopeless. Work with all the persuasion possible, and as the fruit of your faithful efforts you will see in the kingdom of heaven men and women who will be crowned as overcomers, to sing the triumphant song of the conqueror. “They shall walk with Me, in white,” says the First and the Last; “for they are worthy.” [ Revelation 3:4 .] GW 350.2"
"Thou hast a few names even in Sardis which have not defiled their garments; and they shall walk with me in white: for they are worthy."
Ellen White directly references Revelation 3:4 in this passage.