Sahih Bukhari Volume 5, Book 63, Hadith 3899

حَدَّثَنَا الْحُمَيْدِيُّ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا الأَعْمَشُ، قَالَ سَمِعْتُ أَبَا وَائِلٍ، يَقُولُ عُدْنَا خَبَّابًا فَقَالَ هَاجَرْنَا مَعَ النَّبِيِّ صلى الله عليه وسلم نُرِيدُ وَجْهَ اللَّهِ، فَوَقَعَ أَجْرُنَا عَلَى اللَّهِ، فَمِنَّا مَنْ مَضَى، لَمْ يَأْخُذْ مِنْ أَجْرِهِ شَيْئًا، مِنْهُمْ مُصْعَبُ بْنُ عُمَيْرٍ قُتِلَ يَوْمَ أُحُدٍ، وَتَرَكَ نَمِرَةً، فَكُنَّا إِذَا غَطَّيْنَا بِهَا رَأْسَهُ بَدَتْ رِجْلاَهُ، وَإِذَا غَطَّيْنَا رِجْلَيْهِ بَدَا رَأْسُهُ، فَأَمَرَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم أَنْ نُغَطِّيَ رَأْسَهُ، وَنَجْعَلَ عَلَى رِجْلَيْهِ شَيْئًا مِنْ إِذْخِرٍ‏.‏ وَمِنَّا مَنْ أَيْنَعَتْ لَهُ ثَمَرَتُهُ فَهْوَ يَهْدِبُهَا‏

Narrated By Abu Wail : We visited Khabbaba who said, "We migrated with the Prophet 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 woollen cloak. When we covered his head with it, his feet became naked, and when covered his feet, his head became naked. So Allah's Apostle 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."