The Quran Verse
Surah 27:12:
And put your hand into the opening of your [robe]; it will come out white without disease...
The Biblical Contrast
Exodus 4:6:
...and when he took it out, behold, his hand was leprous like snow.
The Bible says God gave Moses a sign by making his hand leprous (a dreaded disease) and then healing it. The Quran repeatedly specifies "white without disease" (bayḍā'a min ghayri sū'in).
Critics argue this is a "theological correction" born of a misunderstanding.
The author of the Quran likely felt that a Prophet of God having a "disease" like leprosy was undignified, so the miracle was changed to a simple "light" or "whiteness." This alters the original biblical sign of God's power over life and decay into a mere magic trick.