Sayyidah Aishah (may Allah be pleased with her) said: The wife of Sayyiduna Uthman bin Maz'un (may Allah be pleased with him), whose name was Khawlah bint Hakim, came to Sayyidah Aishah (may Allah be pleased with her) while she was in a dishevelled state, so she asked her: What is the matter with you? She said: My husband stands (in prayer) at night and fasts by day. Just then the Prophet (peace and blessings be upon him) came in, and Sayyidah Aishah (may Allah be pleased with her) mentioned this to him (peace and blessings be upon him). The Prophet (peace and blessings be upon him) met Uthman (bin Maz'un) (may Allah be pleased with him) and said: "O Uthman! Monasticism (the rigour of renouncing the world) has not been prescribed for us. Is there not an example for you in my life? By Allah, I am the one among you who fears Allah the most and guards His limits the most."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8287