عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ، عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ”أُمِرْتُ بِقَرْيَةٍ تَأْكُلُ الْقُرَى يَقُولُونَ: يَثْرِبُ وَهِيَ الْمَدِينَةُ، تَنْفِي النَّاسَ كَمَا يَنْفِي الْكِيرُ خَبَثَ الْحَدِيدِ“
It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: I have been commanded to migrate to a town which will consume all other towns, that is, it will surpass all in virtue and rank. People call it Yathrib, but it is Madinah. It will expel the hypocrites and wicked people just as a furnace removes impurities from iron.