Hadith 6:209
'Isa ibn Yunus narrated to us, from 'Amr, from al-Hasan, that the Prophet, may Allah bless him and grant him peace, ordered regarding Hamza when he was martyred, so he was washed.
حدثنا عيسى بن يونس عن عمرو عن الحسن أن النبي صلى الله عليه وسلم أمر به بحمزة حين استشهد فغسل