It was narrated that Hisham bin 'Amir said: "We complained to the Messenger of Allah (ﷺ) on the day of Uhud, saying: 'O Messneger of Allah, it is too difficult for us to dig a grave for each person.' The Messenger of Allah (ﷺ) said: 'Dig graves and make them good and deep, and bury two or three in one grave.' They said: 'Who should we put in first, O Messenger of Allah?' He said: 'Put in first the one who knew more Qur'an."' He said: "My father was the third of three in one grave."
Source: sunnah.com
Other translations
Arabic
أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا إِسْحَاقُ بْنُ يُوسُفَ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ أَيُّوبَ، عَنْ حُمَيْدِ بْنِ هِلاَلٍ، عَنْ هِشَامِ بْنِ عَامِرٍ، قَالَ : شَكَوْنَا إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم يَوْمَ أُحُدٍ فَقُلْنَا : يَا رَسُولَ اللَّهِ الْحَفْرُ عَلَيْنَا لِكُلِّ إِنْسَانٍ شَدِيدٌ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم : " احْفِرُوا وَأَعْمِقُوا وَأَحْسِنُوا، وَادْفِنُوا الاِثْنَيْنِ وَالثَّلاَثَةَ فِي قَبْرٍ وَاحِدٍ " . قَالُوا : فَمَنْ نُقَدِّمُ يَا رَسُولَ اللَّهِ قَالَ : " قَدِّمُوا أَكْثَرَهُمْ قُرْآنًا " . قَالَ : فَكَانَ أَبِي ثَالِثَ ثَلاَثَةٍ فِي قَبْرٍ وَاحِدٍ .
sunnah.com