Musannaf Ibn Abi Shayba 33:190

Abu Mu'awiyah and Waki' narrated to us, from al-A'mash, from al-Sha'bi, from al-Nu'man ibn Bashir, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The believers are like one man; if his head complains, the rest of his body calls out for him with fever and sleeplessness."