Apple of the eye
The promise is in Zechariah 2:8, "He that toucheth you toucheth the apple of His eye"; the prayer is Psalm 17:8 "Keep me as the apple of the eye"; the fulfillment Deuteronomy 32:10, "He kept him as the apple of His eye." A different Hebrew word from tappunch, namely, ishon, "little man," i.e. "pupil" (Greek kore) of the eye. Called so from the image formed on the retina. The part most precious and most guarded from attack; which feels most acutely the least hurt, and the loss of which is irreparable.