مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2605
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas (رضي الله عنه) that The Prophet (ﷺ) passed by Abu Qatadah when he was standing beside a man he had killed, and he said: "Leave him and the booty (the slain man's belongings) alone.”
Musnad Ahmad 2620A saheeh hadeeth; this is a saheeh isnad]