The Prophet ﷺ said, "The believer in relation to the people of faith is like the head to the body. The believer feels pain for the people of faith just as the body feels pain for what afflicts the head."
عن النبي ﷺ قال: إن المؤمن من أهل الإيمان بمنزلة الرأس من الجسد، يألم المؤمن لأهل الإيمان، كما يألم الجسد لما في الرأس.
Ahmad (22877) narrated it, and this is his wording, as did Tabarani in Al-Kabir (6/160–161), both through the route of Ahmad bin Hajjaj Marwazi, who said, Abdullah bin Mubarak narrated to us, who said, Musab bin Thabit informed us, who said, Abu Hazim narrated to me, from Sahl bin Saad, and he related it.Musab bin Thabit is daif, but he was not alone in narrating it, rather he was corroborated. Tabarani narrated it in Al-Awsat (4693) through the route of Sawwar bin Umara Ramli, who said, Zuhayr bin Muhammad narrated to us, from Abu Hazim, with similar wording.Zuhayr bin Muhammad is the Tamimi, and the narrations of the people of Syria from him are not sound, and Sawwar bin Umara Ramli is among them. Through these two routes, the hadith rises to the level of hasan.