It was narrated from Ibn ‘Abbas that the Messenger of Allah (ﷺ) commanded that the weapons and armor should be removed from the slain of Uhud, and they should be buried in their clothes stained with blood.
Sunan Ibn Majah Book 6, Hadith 83
← Previous Hadith “Which of them had memorized more Qur’an?” And if one of them was pointed out to him, he would put him in the niche-grave first. And he said: “I am a witness over them.” He commanded that they should be buried with their blood, and that the funeral prayer should not be offered for them and they should not be washed.

Sunan Ibn Majah Book 6, Hadith 82 Next Hadith → “I heard Jabir bin ‘Abdullah say: ‘The Messenger of Allah (ﷺ) commanded that the slain of the battle of Uhud should be returned to the battlefield; they had been moved to Al-Madinah.’”

Sunan Ibn Majah Book 6, Hadith 84