He participated in the battle against Musaylimah as a standard bearer of the Muhajireen and displayed unexpected valour. His people feared that he would show weakness or be too terrified to fight. To them he said, "If you manage to overtake me, what a miserable bearer of the Qur'an I shall be." He then valiantly plunged into the enemy ranks and eventually died in battle.
When Umar was dying, he was questioned about his successor, and he said: ‘If Abu Obaida bin al-Jarrah were alive, I would have made him the khalifa. If Khalid bin al-Walid were alive, I would have appointed him the amir of the Muslims. And if Salim, the client of Abu Hudhaifa, were living today, then I would have designated him as your ruler.' This Salim was a slave who came from Istakhar in Persia. He was emancipated, and became a ‘mawali' (client) of Abu Hudhaifa. He was well-known for his piety. Many Muslims deferred to him in matters of Faith even in the times of Muhammad. Sometimes he led the Muslims in prayer also. He was killed in the Ridda wars during the khilafat of Abu Bakr. He was a devout and God-fearing man.