Praise be to Allah.
If the shaheed dies in battle, he should not be washed and shrouded. This is the view of the majority of scholars, because of the hadeeth of Jaabir ibn ‘Abd-Allah (may Allah be pleased with him), who said that the Prophet (peace and blessings of Allah be upon him) issued orders that the martyrs of Uhud should be buried with their blood and not washed. (Narrated by al-Bukhari, 1346)
Rather they should not be washed, so that the traces of their martyrdom will be left on them, for it was narrated that the Prophet (peace and blessings of Allah be upon him) said: “By the One in Whose hand is my soul, no one is wounded for the sake of Allah – and Allah knows best who is wounded for His sake – but on the Day of Resurrection he will come with a colour like the colour of blood and a fragrance like the fragrance of musk.”
Narrated by al-Bukhari, 2803; Muslim, 1876
‘Abd-Allah ibn Tha’labah narrated that the Prophet (peace and blessings of Allah be upon him) said: “Leave them with their blood, for there is no wound incurred for the sake of Allah, but he will come on the Day of Resurrection bleeding with a colour like the colour of blood but its fragrance will be like the fragrance of musk.”
Narrated by al-Nasaa’i; classed as saheeh by al-Albaani in Saheeh al-Jaami’, 3573
See al-Mughni ma’a al-Sharh al-Kabeer, 2/333; al-Maswoo’ah al-Fiqhiyyah, 26/274
If the shaheed was junub (in a state of impurity following sexual activity), the scholars differed as to whether he should be washed. The more correct view is that he should not be washed because there is no difference between one who is junub and one who is not. The Prophet (peace and blessings of Allah be upon him) did not wash those who were killed at Uhud. Moreover martyrdom is an expiation for everything.
With regard to the report that ‘Abd-Allah ibn Hanzalah was washed by the angels, even if it is saheeh, it does not prove that the shaheed should be washed by human beings, because the angels’ washing him is not something that is visible to us. The rulings for human beings cannot be compared to the rulings for the angels. What happened to Hanzalah (may Allah be pleased with him) was by way of honouring him, not be way of enjoining anything upon us. See al-Sharh al-Mumti’, 5/365.