Hudhaifa reported God’s messenger as saying, “It is not fitting for a believer to demean himself." On being asked how he could demean himself he replied, “By exposing himself to a calamity which he has not the capacity to endure."
Tirmidhi, Ibn Majah and Baihaqi, in Shu'ab al-iman, transmitted it, Tirmidhi saying this is a hasan gharib tradition.