In the Song of Moses, God guarded Israel as the what of His eye?

Answer: Apple

God found Israel in a barren, howling wilderness and "guarded him as the apple of His eye" (Deuteronomy 32:10).

“He found him in a desert land, in a barren, howling wilderness; He surrounded him, He instructed him, He guarded him as the apple of His eye.”— Deuteronomy 32:10 (BSB)