Virtues of Sa'd bin al-Rabi bin Amr al-Khazraji, a man of al-Aqabah (may Allah be pleased with him): his martyrdom and his greeting to the Messenger of Allah (peace and blessings be upon him) with his last breaths

It is narrated from Sayyiduna Abu Dharr (may Allah be pleased with him) that he said: When the Messenger of Allah (peace and blessings be upon him) had finished with the Battle of Uhud, he passed on his way by Mus'ab bin Umayr, who had been martyred, and he (peace and blessings be upon him) recited this verse: "Among the believers are men who have been true to the covenant they made with Allah" [Surah al-Ahzab: 23].
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.

Kharijah bin Zayd bin Thabit narrates from his father that he said: On the day of the Battle of Uhud, the Messenger of Allah (peace and blessings be upon him) sent me to look for Sa'd bin al-Rabi', and said to me: "If you find him, convey my greeting of peace to him and say to him that the Messenger of Allah (peace and blessings be upon him) asks: 'How do you find yourself?'" Zayd says: I began going around among the slain, and I found him in his last breaths. He had seventy wounds from spears, swords and arrows. I said to him: "O Sa'd, the Messenger of Allah (peace and blessings be upon him) sends you greetings of peace and asks: 'Tell me, how do you find yourself?'" He said: "Peace be upon the Messenger of Allah (peace and blessings be upon him), and peace be upon you. Say to him: 'O Messenger of Allah, I find the fragrance of Paradise within me.' And say to my people, the Ansar: 'You will have no excuse before Allah if any harm reaches the Messenger of Allah (peace and blessings be upon him) while a single eye among you still blinks (that is, while even one of you is alive).'" The narrator says: Then his soul departed, may Allah have mercy on him.
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.