Musnad Ahmad 128:6

Yahya ibn Sa'id narrated to us, from Shu'bah, who said: Mu'awiyah ibn Qurrah narrated to me, from his father, from the Prophet, peace and blessings of Allah be upon him, who said: "When the people of Ash-Sham become corrupt, there is no good in you. And a group of my Ummah will continue to be aided; those who abandon them will not harm them, until the Hour is established."