Musnad Ahmad 1678

It was narrated from Salim, from "Abdullah, that ‘AbdurRahman bin "Awf told "Umar bin al-Khattab, when he was marching towards Syria, that the Prophet (ﷺ) said: "The people who came before you were punished with this sickness. If you hear of it in some land, do not enter it; and if it happens in a land where you are, do not leave it, fleeing from it." So" Umar bin al-Khattab turned back from Syria,