Yahya related to me from Malik from Muhammad ibn al-Munkadir fromJabir ibn Abdullah that a Bedouin took an oath of allegiance in Islamwith the Messenger of Allah, may Allah bless him and grant him peace.A fever befell the Bedouin at Madina. He came to the Messenger ofAllah, and said, "Messenger of Allah, release me from my pledge." TheMessenger of Allah, may Allah bless him and grant him peace, refused.Then he came to him again and said, "Release me from my pledge." TheMessenger of Allah may Allah bless him and grant him peace, refused.Then he came again and said, "Release me from my pledge." He refused.Then he came again and said, "Release me from my pledge." He refused.The Bedouin left and the Messenger of Allah, may Allah bless him andgrant him peace, said, "Madina is like the blacksmith's furnace. Itremoves the impurities and purifies the good."
USC-MSA web (English) reference: Book 45, Hadith 4
Arabic reference: Book 45, Hadith 1604