Why did the bedouin visit Allah's Apostle (saw) three times in order to cancel his Pledge of allegiance?
 Narrated Jabir bin `Abdullah:                     A bedouin gave the Pledge of allegiance to Allah's Apostle for Islam. Then the bedouin got fever at Medina, came to Allah's Apostle and said, "O Allah's Apostle! Cancel my Pledge," But Allah's Apostle refused. Then he came to him (again) and said, "O Allah's Apostle! Cancel my Pledge." But the Prophet refused Then he came to him (again) and said, "O Allah's Apostle! Cancel my Pledge." But the Prophet refused. The bedouin finally went out (of Medina) whereupon Allah's Apostle said, "Medina is like a pair of bellows (furnace): It expels its impurities and brightens and clears its good.