It is narrated from Sayyiduna Abu Qatadah (may Allah be pleased with him) that he said: We went out with the Messenger of Allah (peace and blessings be upon him) on the day of Hunayn. When we met the enemy, the Muslims were in retreat. I saw a man of the polytheists overpowering a man of the Muslims. (Abu Qatadah says:) I turned around and came at him from behind, and I struck him on the neck. He came at me and seized me so tightly that I felt my soul being taken; then he died and let go of me. I met Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) and asked: "What is the state of the Muslims?" Sayyiduna Umar (may Allah be pleased with him) said: "It is the decree of Allah." Then the people returned to victory. The Messenger of Allah (peace and blessings be upon him) said: "Whoever kills someone and has a witness to it, the belongings of the slain man are his." I stood up and said: "Who will testify for me?" (When no one stood up,) I sat down. He (peace and blessings be upon him) said it a second time, and I stood up again and said: "Who will testify for me?" (When no one rose,) I sat down. Then he (peace and blessings be upon him) said the same thing a third time, and I stood up again. The Messenger of Allah (peace and blessings be upon him) said: "Abu Qatadah! What is the matter with you?" I told him the whole story. A man said: "O Messenger of Allah (peace and blessings be upon him)! He has spoken the truth, and the man's belongings are with me, so satisfy him (on my behalf)." Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) said: "By Allah! He will never do that: (take) from a lion of Allah who fought for Allah and give you his spoils." The Messenger of Allah (peace and blessings be upon him) said: "He has spoken the truth, so give it to him." Sayyiduna Abu Qatadah (may Allah be pleased with him) said: He (that man) gave me the belongings. I sold the coat of mail and with its price bought an orchard among Banu Salimah; it was the first property I acquired in Islam.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12761