It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever is afflicted with a calamity in his wealth or his body and conceals it, not complaining about it to people, it is a right upon Allah that He forgive him."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11390