Musnad Ahmad 908:26

Abdullah ibn Idris narrated to us, he said: And I heard al-A’mash narrating from Shaqiq, from Khabbab, who said: We migrated with the Messenger of Allah, peace and blessings of Allah be upon him, and among us were those who died and did not eat anything of their reward. Among them was Mus’ab ibn Umayr, who did not leave behind anything except a garment; if we covered his head with it, his feet would appear, and if we covered his feet, his head would appear. The Messenger of Allah, peace and blessings of Allah be upon him, said to us: "Cover his head." And we placed *idhkhir* (lemon grass) upon his feet. He said: And among us are those whose fruits have ripened, and he is harvesting them.