Musnad Ahmad 772:1

Abdullah said: Mu'awiyah ibn Abdullah ibn Mu'awiyah ibn 'Asim ibn al-Mundhir ibn al-Zubayr narrated to us, Salam Abu al-Mundhir al-Qari' narrated to us, 'Asim ibn Bahdalah narrated to us, from al-Sha'bi, or Khaythamah, from al-Nu'man ibn Bashir, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The likeness of the Muslims is only as one man; if any part of him aches, the rest of his body calls out for him [in sympathy]."