Anas (May Allah be pleased with him) said:
My uncle Anas bin An-Nadr (May Allah be pleased with him) was absent from the battle of Badr and he said: "O Messenger of Allah! I was absent from the first battle you fought against the pagans, and if Allah let me participate in a battle against the pagans, Allah will see what I do." So he encountered the day of Uhud Battle. The Muslims left the positions (the Prophet ﷺ told them to keep) and were defeated, he said: "O Allah! excuse these people (i.e., the Muslims) for what they have done, and I am clear from what the pagans have done". Then he went forward with his sword and met Sa'd bin Mu'adh (fleeing) and said to him: "By the Rubb of the Ka'bah! I can smell the fragrance of Jannah from a place closer than Uhud Mount". Sa'd said: "O Messenger of Allah, what he did was beyond my power". Anas said: "We saw over eighty wounds on his body caused by stabbing, striking and shooting of arrows and spears. We found that he was killed, and mutilated by the polytheists. Nobody was able to recognize him except his sister who recognized him by the tips of his fingers." Anas (May Allah be pleased with him) said: "We believe that the Ayah 'Among the believers are men who have been true to their covenant with Allah [i.e., they have gone out for Jihad (holy fighting), and showed not their backs to the disbelievers]...' (33:23), refers to him and his like".

[Al-Bukhari and Muslim].

الخامس عشر: عن أنس رضي الله عنه، قال: غاب عمي أنس ابن النضر رضي الله عنه، عن قتال بدر، فقال: يارسول الله غبت عن أول قتال قاتلت المشركين، لئن الله أشهدني قتال المشركين ليرين الله ما أصنع. فلما كان يوم أحد انكشف المسلمون، فقال اللهم أعتذر إليك مما صنع هؤلاء - يعني أصحابه- وأبرأ إليك مما صنع هؤلاء- يعني المشركين- ثم تقدم فاستقبله سعد بن معاذ، فقال: ياسعد بن معاذ الجنة ورب الكعبة، إني أجد ريحها من دون أحد. قال سعد: فما استطعت يا رسول الله ما صنع! قال أنس: فوجدنا به بضعاً وثمانين ضربة بالسيف، أو طعنة برمح ، أو رمية بسهم، ووجدناه قد قتل ومثل به المشركون فما عرفه أحد إلا أخته ببنانه. قال أنس: كنا نرى أو نظن أن هذه الآيه نزلت فيه وفي أشباهه: {من المؤمنين رجال صدقوا ما عهدوا الله عليه} (( الأحزاب: 23)) إلى آخرها. ((متفق عليه)).