The martyrdom of Salim and his patron Abu Hudhayfah (may Allah be pleased with them)

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Learn the Qur'an from these four people: from Abdullah bin Mas'ud, from Mu'adh, from Ubayy (bin Ka'b), and from Salim, the freed slave of Abu Hudhayfah."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.

Muhammad bin Umar narrates from his teachers that Salim (may Allah be pleased with him), the freed slave of Sayyiduna Abu Hudhayfah, was originally the slave of an Ansari woman, Thubaytah bint Ya'ar, who was married to Abu Hudhayfah (may Allah be pleased with him). Abu Hudhayfah adopted him, and so he used to be called Salim bin Abi Hudhayfah. But when this verse of the Qur'an was revealed: "Call them by (the names of) their (real) fathers" [Surah al-Ahzab: 5], he came to be called Salim, the freed slave of Abu Hudhayfah. He was martyred in the Battle of Yamamah in the year 12 AH, and on the battlefield his head was found at the feet of Abu Hudhayfah, or the feet of Abu Hudhayfah at his head. Musa bin Uqbah says that his real name was Salim bin Ma'qil and that he was from Istakhr (in Persia).