Musannaf Ibn Abi Shayba 28:487

Abu Usama narrated to us, he said: Mus'ab bin Sulaym al-Zuhri narrated to us, he said: Anas bin Malik narrated to us, he said: When Abu Musa was sent to Basra, among those who were sent was al-Bara' bin Malik, and he was behind him. He (Abu Musa) used to say to him: "Choose a task." Al-Bara' said: "And will you give me what I ask of you?" He said: "Yes." He said: "As for me, I do not ask you for the governorship of a city, nor the collection of land tax, but give me my bow, my horse, my spear, and my sword, and leave me to the Jihad in the way of Allah." So he sent him over an army, and he was the first to be killed.