Exodus 4:7

And he said, put thine hand, &c.— The leprosy was generally reckoned a disease incurable by human art. See Celsus, lib. 5: ch. 28. The inflicting, therefore, and instantaneously curing this disease, was a demonstrative proof of Divine power. See Leviticus 13:3. Numbers 12:10. 2 Kings 5:27. Bishop Patrick conjectures, that this part of Moses's history being imperfectly known among the Heathens, had given occasion to the fabulous story which was invented in future ages, that Moses and the Israelites were infected with the leprosy, and driven out of Egypt on account of that and other scurvy diseases; for so the tale was told in Manetho's history, and is still extant in Justin and Tacitus.