The Messenger of Allah ﷺ said, "The likeness of the believers in their mutual love, mercy, and compassion is like a single body. When one limb of it suffers, the rest of the body responds with sleeplessness and fever."
قال رسول الله ﷺ: مثل المؤمنين في توادهم وتراحمهم وتعاطفهم مثل الجسد، إذا اشتكى منه عضو تداعى له سائر الجسد بالسهر والحمى.
Bukhari narrated it in the Book of Manners (6011), and Muslim narrated it in the Book of Kindness, Ties of Kinship, and Manners (2586), both of them through Zakariya, from Amir Shaybi, who said, I heard Numan bin Bashir say, and then he mentioned it. The wording given is that of Muslim, and Bukhari's wording is similar.