Sahih al-Bukhari Hadith 2805

Narrated Anas: My uncle Anas bin An-Nadr was absent from the Battle of Badr. He said, "O Allah's Messenger (ﷺ)! I was absent from the first battle you fought against the pagans. (By Allah) if Allah gives me a chance to fight the pagans, no doubt. Allah will see how (bravely) I will fight." On the day of Uhud when the Muslims turned their backs and fled, he said, "O Allah! I apologize to You for what these (i.e. his companions) have done, and I denounce what these (i.e. the pagans) have done." Then he advanced and Sa`d bin Mu`adh met him. He said "O Sa`d bin Mu`adh ! By the Lord of An-Nadr, Paradise! I am smelling its aroma coming from before (the mountain of) Uhud," Later on Sa`d said, "O Allah's Apostle! I cannot achieve or do what he (i.e. Anas bin An-Nadr) did. We found more than eighty wounds by swords and arrows on his body. We found him dead and his body was mutilated so badly that none except his sister could recognize him by his fingers." We used to think that the following Verse was revealed concerning him and other men of his sort: "Among the believers are men who have been true to their covenant with Allah.........." (33.23) His sister Ar-Rubbaya' broke a front tooth of a woman and Allah's Messenger (ﷺ) ordered for retaliation. On that Anas (bin An-Nadr) said, "O Allah's Messenger (ﷺ)! By Him Who has sent you with the Truth, my sister's tooth shall not be broken." Then the opponents of Anas's sister accepted the compensation and gave up the claim of retaliation. So Allah's Messenger (ﷺ) said, "There are some people amongst Allah's slaves whose oaths are fulfilled by Allah when they take them."