Jabir reported that the Messenger of Allah ﷺ would place two of those killed at Uhud together in a single garment, then he would ask, "Which of them had memorized more of the Quran?" When one of them was pointed out to him, he would put that one first in the grave and say, "I will be a witness over these on the Day of Resurrection." He ordered that they be buried in their blood, without being washed, and he did not perform the funeral prayer over them.
قال كان رسول الله يجمع بين ﷺ الرجلين من قتلى أحد في ثوب واحد ثم يقول: أيهم أكثر أخذا للقرآن؟ فإذا أشير له إلى أحد قدمه في اللحد وقال: أنا شهيد على هؤلاء يوم القيامة، وأمر بدفنهم بدمائهم، ولم يصل عليهم، ولم يغسلوا.
Bukhari narrated it in al-Maghazi (4079) from Qutayba bin Saeed, who said, Layth narrated to us, from Ibn Shihab, from Abdul-Rahman bin Kaab bin Malik, from Jabir bin Abdullah, who said, then he mentioned it.For more, see the Book of Funerals.