His uncle (Anas bin An-Nadr) was absent from the battle of Badr and he said, "I was absent from the first battle of the Prophet (i.e. Badr battle), and if Allah should let me participate in (a battle) with the Prophet, Allah will see how strongly I will fight." So he encountered the day of Uhud battle. The Muslims fled and he said, "O Allah ! I appeal to You to excuse me for what these people (i.e. the Muslims) have done, and I am clear from what the pagans have done." Then he went forward with his sword and met Sad bin Mu'adh (fleeing), and asked him, "Where are you going, O Sad? I detect a smell of Paradise before Uhud." Then he proceeded on and was martyred. No-body was able to recognize him till his sister recognized him by a mole on his body or by the tips of his fingers. He had over 80 wounds caused by stabbing, striking or shooting with arrows.
Sahih al-Bukhari Book 64, Hadith 94
← Previous Hadith We migrated in the company of Allah's Messenger (ﷺ), seeking Allah's Pleasure. So our reward became due and sure with Allah. Some of us have been dead without enjoying anything of their rewards (here), and one of them was Mus'ab bin 'Umar who was martyred on the day of the battle of Uhud, and did not leave anything except a Namira (i.e. a sheet in which he was shrouded). If we covered his head with it, his feet became naked, and if we covered his feet with it, his head became naked. So the Prophet (ﷺ) said to us, "Cover his head with it and put some Idhkhir (i.e. a kind of grass) over his feet or throw Idhkhir over his feet." But some amongst us have got the fruits of their labor ripened, and they are collecting them.

Sahih al-Bukhari Book 64, Hadith 93 Next Hadith → When we wrote the Holy Qur'an, I missed one of the Verses of Surat-al-Ahzab which I used to hear Allah's Messenger (ﷺ) reciting. Then we searched for it and found it with Khuza`ima bin Thabit Al-Ansari. The Verse was:-- 'Among the Believers are men Who have been true to Their Covenant with Allah, Of them, some have fulfilled Their obligations to Allah (i.e. they have been Killed in Allah's Cause), And some of them are (still) waiting" (33.23) So we wrote this in its place in the Qur'an.

Sahih al-Bukhari Book 64, Hadith 95