Commentaire sur Les Psaumes 17:8

as the apple Heb. (כאישון). That is the pupil (lit. the black) of the eye, on which the vision depends. Because it is black, it is called אישון, an expression of darkness, and the Holy One, blessed be He, prepared a guard for it, viz. the eyelids, which constantly cover it.

Keep me as the pupil (אישׁון) of the ball of the eye: – as a man guards the pupil of his eye – that is, the black part through which the light (passes). It is called the אישׁון (lit. little man), because the image of a man is seen in it; and the waw and nun mark the diminutive, because the image is diminutive; so also the ון of שׁבתון (sabbath keeping), with the idea of emphasising its holiness. So also, with the addition of yodh, אמינון in 2 Sam. 13:20. אישון is in the construct before בת, and (with it) forms one expression; בת (lit. daughter) is a substantive, (denoting) the eyeball through which the light (passes), while pupil is a descriptive term because the image of a man is seen in it.

And hide me in the shadow of Thy wings, –