Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings be upon him) said: I have been commanded to migrate to a city which will consume other cities (i.e., it will become the leader of them all). The hypocrites call it Yathrib, but its name is Madinah. It expels (evil) people just as a furnace removes the impurities from iron.

Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) narrated that a Bedouin pledged allegiance to the Messenger of Allah (peace and blessings be upon him) for Islam. Then he was afflicted with fever in Madinah, so he came to the Messenger of Allah (peace and blessings be upon him) and said, "O Messenger of Allah, cancel my pledge." The Messenger of Allah (peace and blessings be upon him) refused. Then he came again and said, "Cancel my pledge." The Messenger of Allah (peace and blessings be upon him) refused again. Then he came and demanded the cancellation of his pledge. The Messenger of Allah (peace and blessings be upon him) refused again. After that, he left (Madinah) on his own. The Messenger of Allah (peace and blessings be upon him) said regarding this, "Madinah is like a furnace; it removes its impurities and retains the pure."

Sayyiduna Zaid bin Thabit (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings be upon him) said: "This is Madinah Tayyibah; it expels impurity just as fire removes the filth from silver."