Sahih Muslim 1384
Sahih Muslim · Book 15: The Book of Pilgrimage · Al-Madinah eliminates its Dross and it is also called Tabah, and Taibah
Zaid b. Thabit reported Allah's Apostle (ﷺ) as saying:
وَحَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، - وَهُوَ الْعَنْبَرِيُّ - حَدَّثَنَا أَبِي ، حَدَّثَنَا شُعْبَةُ ، عَنْ عَدِيٍّ، - وَهُوَ ابْنُ ثَابِتٍ - سَمِعَ عَبْدَ اللَّهِ بْنَ يَزِيدَ ، عَنْ زَيْدِ بْنِ ثَابِتٍ ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّهَا طَيْبَةُ - يَعْنِي الْمَدِينَةَ - وَإِنَّهَا تَنْفِي الْخَبَثَ كَمَا تَنْفِي النَّارُ خَبَثَ الْفِضَّةِ" .
It is Taiba, thereby meaning Medina. It drives away impurity just as fire removes the impurity of silver.