Jami` at-Tirmidhi: Book 47, Hadith 252

Narrated Anas: “My paternal uncle Anas bin An-Nadr – after whom I was named – did not participate in the battle of Badr with the Messenger of Allah (ﷺ). This distressed him and he said: ‘I was absent from the first battle which the Messenger of Allah (ﷺ) attended. By Allah! If Allah gives me the opportunity to participate in another battle along with the Messenger of Allah (ﷺ), then Allah will see what I will do!'” He said: “He did not want to say more than that. A year later, he attended the battle of Uhud, where he saw Sa’d bin Mu’adh and said: ‘O Abu ‘Amr where are you going?’ He said: ‘I long for the fragrance of Paradise and I have found it near the mountains of Uhud.’ He fought them until he was killed. They found more than eighty wounds on his body, be they from blows of a sword, puncture wounds, or arrows. My paternal aunt Ar-Ruba’i bin An-Nadr said: ‘I could not recognize my brother except by his finger tips.’ And this Ayah was revealed: ‘Among the believers are men who have been true to their covenant with Allah; of them some have fulfilled their vow, and some of them are still waiting, but they have never changed in the least (33:23).'”