سنن النسائي

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."