● Definition: A report whose chain appears sound but contains a hidden defect in the chain or text that affects its soundness.
● Example: One student named ʿAmr ibn Dīnār in the chain, while the other students named ʿAbdullāh ibn Dīnār.
● Reason: The chain appeared sound, but comparison revealed a hidden difference in the narrator's name, so this illustrates muʿallal.