Surah 20. Ta-Ha, Ayah 22

I.e., strangely luminescent by virtue of the prophethood to which he had been raised. (See also note [85] on 7:108 .)

 Moses, who was dark-skinned, was asked to put his hand under his armpit. When he took it out it was shining white, but not out of a skin condition like melanoma.

The second of the greater Miracles shown to Moses was the "White (shining) Hand". Ordinarily, when the skin becomes white, it is a sign of disease, leprosy or something loathsome. Here there was no question of disease: on the contrary, the hand was glorified, and it shone as with a divine light. Such a miracle was beyond Egyptian or human magic.