Abd al-Rahman bin Ka'b bin Malik (may Allah have mercy on him) narrates that Jabir (may Allah be pleased with him) informed him that the Messenger of Allah (peace and blessings be upon him) would put two men from those slain at Uhud together in a single cloth and ask: "Which of them had learned more of the Qur'an?" Then whoever was pointed out, he would put him forward in the lahd (niche of the grave), and he (peace and blessings be upon him) said: "I will be a witness over these on the Day of Resurrection." And he (peace and blessings be upon him) ordered: "Bury them with their blood." Their funeral prayer was not offered, nor were they washed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6795