Concept:The admonition "Do not be angry" is a well-known saying of the Prophet Muhammad (peace be upon him) recorded in Imam an-Nawawi's collection of forty hadiths.Explanation:In the book of An-Nawawi's Forty Hadith, each hadith is numbered for easy reference.The hadith that contains the advice "Do not be angry" is specifically numbered as hadith sixteen.This saying teaches self-control and avoiding anger.Answer:C. 16