CHAPTER: Making The Grave Deep.
Narrated Hisham ibn Amir: The Ansar came to the Messenger of Allah صلی اللہ علیہ وسلم on the day of Uhud and said: We have been afflicted with wound and fatigue. What do you command us? He said: Dig graves, make them wide, bury two or three in a single grave. He was asked: Which of them should be put first? He replied: The one who knew the Quran most. He (Hisham) said: My father Amir died on the day and was buried with two or one.
The tradition mentioned above has also been transmitted by Humaid bin Hilal with a different chain of transmitters and to the same effect. This version adds: And deepen (the graves).
This tradition has also been transmitted by Saad bin Hisham bin Amir with a different chain of narrators.