Musnad Ahmad 907:216

Bahz and Surayj narrated to us, they said: Hammad ibn Salamah narrated to us, from Simak, from Jabir ibn Samurah, who said: The people used to say: Yathrib and al-Madinah. So the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah has named it Tabah." Surayj said: Yathrib is al-Madinah.