Sahih al-Bukhari, Volume 2, Book 23, Hadith 430 (USC-MSA) ⓘ
Narrated Jabir: The Prophet said, "Bury them (i.e. martyrs) with their blood." (that was) On the day of the Battle of Uhud. He did not get them washed.
حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا لَيْثٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ كَعْبٍ، عَنْ جَابِرٍ، قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " ادْفِنُوهُمْ فِي دِمَائِهِمْ " . ـ يَعْنِي يَوْمَ أُحُدٍ ـ وَلَمْ يُغَسِّلْهُمْ.
also referenced under: Book 23, Hadith 102 (In-Book) & Hadith 1346 (DarusSalam)