The Messenger of Allah (ﷺ) combined two persons from among the martyrs of Uhud (in one garment), and said: Which of the two has learnt the Qur'an more ? When one of them was pointed to him, he advanced him in the grave, saying: I shall be witness to all these (martyrs) on the Day of Judgement. He then ordered them to be buried without being washed.
Sunan Abi Dawud Book 21, Hadith 50