Musab bin Umayr was killed on the day of Uhud, and he had nothing to be shrouded in except a striped cloak. Whenever we covered his head with it, his feet would stick out, and whenever we covered his feet, his head would stick out. So the Messenger of Allah ﷺ said, "Cover his head with it, and place some idhkhir grass over his feet."
حدثنا محمد بن كثير أخبرنا سفيان عن الأعمش عن أبي وائل
إن مصعب بن عمير قتل يوم أحد ولم يكن له إلا نمرة كنا إذا غطينا بها رأسه خرج رجلاه وإذا غطينا رجليه خرج رأسه فقال رسول الله ﷺ غطوا بها رأسه واجعلوا على رجليه شيئا من الإذخر
Reference. Bukhari narrated it in Merits of the Ansar, the chapter on the migration of the Prophet ﷺ and his companions to Madinah, no. 3913, and no. 6432, from Muhammad bin Kathir Abdi, and Muslim narrated it in Funerals, the chapter on the shroud of the deceased, no. 940, from the hadith of Sufyan Thawri, with the same wording.