Mujibah narrates from his father or his uncle (may Allah be pleased with him) (the narrator is in doubt) that he said: I came to the Messenger of Allah (peace and blessings be upon him) and said: O Messenger of Allah! I am the man who came to you last year. He (peace and blessings be upon him) said: "Why is it that I see your body has become thin?" I said: O Messenger of Allah! Since I pledged allegiance to you, I have not eaten anything during the day. He (peace and blessings be upon him) said: "Who ordered you to torment yourself?" I said: O Messenger of Allah! I am strong. He (peace and blessings be upon him) said: "Fast the month of patience (Ramadan) and two days after it." I said: I am strong. He (peace and blessings be upon him) said: "Fast the month of patience and three days after it, and fast in the sacred months as well."
Hadith Referenceالمعجم الكبير للطبراني / مسند من يعرف بالكنى / 19104