Anas bin Malik narrated that the Messenger of Allah (S.A.W) said:
"The parable of the ill when he is cured and becomes healthy is that of hail that falls from the heavens in its purity and its color." (FR)
English reference (FR): Vol. 4, Book 2, Hadith 2086 (FR)
Arabic reference (FR): Book 28, Hadith 2230 (FR)