The Prophet ﷺ used to wrap two of the slain of Uhud in a single garment, then ask, "Which of them had memorized more of the Quran?" When one of them was indicated to him, he placed that one first in the grave and said, "I will be a witness over these on the Day of Resurrection." He commanded that they be buried in their blood, and they were neither washed nor prayed over.
حدثنا قتيبة حدثنا الليث عن ابن شهاب عن عبد الرحمن بن كعب بن مالك أن
أن النبي ﷺ كان يجمع بين الرجلين من قتلى أحد في الثوب الواحد ثم يقول أيهما أكثر أخذا للقرآن فإذا أشير له إلى أحدهما قدمه في اللحد وقال أنا شهيد على هؤلاء يوم القيامة وأمر بدفنهم في دمائهم ولم يصل عليهم ولم يغسلوا
SourcingBukhari also narrated it in the Book of Funerals, Chapter on burying two or three men in one grave, hadith no. 1343, 1345, from the hadith of Layth bin Saad through this same chain. On this subject there is also a narration from Anas bin Malik [previously mentioned at 1016].