Alsiraj Official Website
Sayings (Hadiths) of Prophet Muhammad
About the permissibility of complaining of an illness
1-Narrated Adbullah ibn Masoud: I visited Allah’s Messenger while he was suffering from a high fever. I said: o Allah’s Messenger! You have a high fever. He said: “yes. I have as much fever as two men of you." I said: is it because you will have a double reward? He said:"yes. It is so. No Muslim is afflicted with any harm, even if it were the prick of a thorn, but Allah expiates his sins because of it, as a tree sheds its leaves."
(Bukhari)