"The destruction that befell the northern kingdom was a direct judgment from Heaven. The Assyrians were merely the instruments that God used to carry out His purpose. Through Isaiah, who began to prophesy shortly before the fall of Samaria, the Lord referred to the Assyrian hosts as “the rod of Mine anger.” “The staff in their hand,” He said, “is Mine indignation.” Isaiah 10:5 . PK 291.3"
"O Assyrian, the rod of mine anger, and the staff in their hand is mine indignation."
Ellen White directly references Isaiah 10:5 in this passage.