Rifa'ah bin Sahl al-Juhani relates that he heard Sayyiduna Sahl bin Hunayf (may Allah be pleased with him) say: I heard the Messenger of Allah (peace and blessings be upon him), as he (peace and blessings be upon him) was coming out of one of his houses, trailing his cloak, saying: "People will (keep settling until they) reach Sal' (the hill); then a time will come upon Madinah when a traveller will pass through one of its districts and say: This (place) was once inhabited. (He will say this) because of the long passage of time and the effacement of its traces."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5576