(45) باب هِجْرَةُ النَّبِيِّ صلى الله عليه وسلم وَأَصْحَابِهِ إِلَى الْمَدِينَةِ
Narrated Abu Wail:
We visited Khabbaba who said, "We migrated with the Prophet (ﷺ) for Allah's Sake, so our reward became due and sure with Allah. Some of us passed away without taking anything of their rewards (in this world) and one of them was Mus`ab bin `Umar who was martyred on the day (of the battle) of Uhud leaving a striped woolen cloak. When we covered his head with it, his feet became naked, and when covered his feet, his head became naked. So Allah's Messenger (ﷺ) ordered us to cover his head and put some Idhkhir (i.e. a special kind of grass) on his feet. (On the other hand) some of us have had their fruits ripened (in this world) and they are collecting them."
Reference: Sahih al-Bukhari 3897
In-book reference: Book 63, Hadith 123
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 5, Book 58, Hadith 237