It is narrated from Hazrat Jabir (may Allah be pleased with him) that people used to call Madinah Munawwarah as Yathrib. The Prophet (peace and blessings be upon him) said: Allah Almighty has named Madinah Munawwarah as "Tayyibah".
Hadith Referenceمسند احمد / أول مسند البصريين / 21022