It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "It is not fitting for a believer to humiliate himself." It was said: O Messenger of Allah, how does he humiliate himself? He (peace and blessings be upon him) said: "By exposing himself to a trial that he cannot bear."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13450