Shaqiq bin Salamah (may Allah have mercy on him) said: Sayyiduna Khabbab (may Allah be pleased with him) narrated to us; he said: We emigrated with the Messenger of Allah (peace and blessings be upon him), seeking the pleasure of Allah, the Mighty and Majestic, and our reward became due upon Allah. Among us was one who passed away (from this world) without consuming anything of his reward; among them was Sayyiduna Mus'ab bin Umayr (may Allah be pleased with him). He was martyred on the day of Uhud, and we found nothing to shroud him in except a striped woollen cloak. When we covered his head with it, his feet were exposed, and when we covered his feet, his head was exposed. So the Messenger of Allah (peace and blessings be upon him) ordered us to cover his head and place idhkhir grass over his feet. And among us are those whose fruit has ripened for them and they are picking it.
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3646