Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) says that when the Battle of Uhud took place, the Messenger of Allah (peace and blessings be upon him) looked at the slain (martyrs) of Uhud and said: "Wrap them in their blood, for indeed I am a witness over them." One, two and three men were buried in a single grave, and he (peace and blessings be upon him) would ask: "Which of them recited more of the Qur'an?" Then he would be put forward. Sayyiduna Jabir (may Allah be pleased with them both) says: On that day my father and my paternal uncle were buried in a single grave.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6801