Musnad Ahmad 937:178

'Affan narrated to us, Wuhayb narrated to us, 'Abdullah ibn 'Uthman ibn Khuthaym narrated to us, from Mujahid, from Ibrahim—meaning Ibn al-Ashtar—that death approached Abu Dharr while he was in al-Rabadhah, and his wife wept. He said, "What makes you weep?" She said, "I weep because I have no power over your soul, and I do not have a garment that can suffice as a shroud for you." He said, "Do not weep, for I heard the Messenger of Allah (peace and blessings of Allah be upon him) one day, while I was with him among a group, say: 'A man among you shall surely die in a desolate land, and a group of believers shall witness him.'" He said, "Everyone who was with me in that gathering has died in a group or a company, and none of them remains except me. And I have reached the morning in this desolate land, dying. So watch the road, for you shall see what I say, for by Allah, I have not lied, nor have I been lied to." She said, "And how can that be, when the pilgrims have ceased?" He said, "Watch the road." He said, "While she was like that, suddenly she saw a group of men whose mounts were moving swiftly with them, as if they were vultures. The group approached until they stood over her and said, 'What is the matter with you?' She said, 'A man of the Muslims is dying; shroud him and you shall be rewarded for him.' They said, 'Who is he?' She said, 'Abu Dharr.'" They sacrificed their fathers and mothers for him, and they placed their whips upon their necks, rushing toward him. He said, "Rejoice, for you are the group about whom the Messenger of Allah (peace and blessings of Allah be upon him) said what he said. Rejoice, for I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'There are no two Muslims who lose two or three children between them, and they seek the reward from Allah and are patient, but they shall never see the Fire.' "And now I have reached this day where you see me. If any garment of mine could suffice me, I would not be shrouded except in it. So I adjure you by Allah that no man among you who was an amir (commander), an 'arif (leader of a group), or a barid (courier) should shroud me." Every man among the group had attained something of that, except for a youth from the Ansar who was with the group. He said, "I am your companion. I have two garments in my saddlebag from the spinning of my mother, and I shall find these two garments of mine that I am wearing." He said, "You are my companion, so shroud me."