The Book of the Believer · Hadith 85 (#Ḥadīth #2)
Chapter 3 | The bond that Allah has set amongst the believers
85 - وعن أحدهما (ع) أنه قال المؤمِن أخو المؤمن كالجسَدِ الواحد، إذا سقط منه شئٌ تَداعى سائرُ الجسد.
85. It has been reported that Abu Ja'far or Abu 'Abd Allah said: Believers are brothers of one another, like one physical body from which when one part is lost, the whole body becomes affected.
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).