It was narrated from Sa'd bin Hisham bin 'Amir that his father said:"Many people were wounded on the day of Uhud and complaints were made to the Messenger of Allah about that. He said: 'Dig graves and make them good and wide, and bury two or three in a grave, and put in first the one who knew the Qur'an most."'
أَخْبَرَنِي إِبْرَاهِيمُ بْنُ يَعْقُوبَ، قَالَ أَنْبَأَنَا سُلَيْمَانُ بْنُ حَرْبٍ، قَالَ حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ أَيُّوبَ، عَنْ حُمَيْدِ بْنِ هِلاَلٍ، عَنْ سَعْدِ بْنِ هِشَامِ بْنِ عَامِرٍ، عَنْ أَبِيهِ، قَالَ : اشْتَدَّ الْجِرَاحُ يَوْمَ أُحُدٍ فَشُكِيَ ذَلِكَ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ : " احْفِرُوا وَأَوْسِعُوا وَأَحْسِنُوا، وَادْفِنُوا فِي الْقَبْرِ الاِثْنَيْنِ وَالثَّلاَثَةَ، وَقَدِّمُوا أَكْثَرَهُمْ قُرْآنًا " .
Nesai
The Book of Funerals • Hadith 2016