It is narrated from Hazrat Bara’ (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Whoever calls Madinah by the name of Yathrib should seek forgiveness from Allah; it is Taabah, Taabah (pure).
Hadith Referenceمسند احمد / أول مسند الكوفيين / 18519
Hadith Gradingحکم دارالسلام:إسناده ضعيف لضعف يزيد بن أبى زياد، ولاضطرابه فيه