It was narrated from Jabir bin ‘Abdullah that a Bedouin pledged Islam to the Messenger of Allah صلی اللہ علیہ وآلہ وسلم then the Bedouin was stricken with the fever in Al- Madinah. So he came to the Messenger of Allah صلی اللہ علیہ وآلہ وسلم and said: “Messenger of Allah صلی اللہ علیہ وآلہ وسلم, cancel my pledge,” but he refused. Then he came to him again and said: “Cancel my pledge,” but he refused. Then the Bedouin left (Al Madinah) and the Messenger of Allah صلی اللہ علیہ وآلہ وسلم said: “Al-Madinah is like the bellows; it expels its dross and brightens its good.” (Sahih)