Musannaf Ibn Abi Shayba 28:557

Abu Mu'awiyah narrated to us, from al-Shaybani, from Muhammad ibn Ubayd Allah, from Sa'd ibn Abi Waqqas, who said: When the day of Badr arrived, I killed Sa'id ibn al-'As and took his sword, and my sword was called "Dhu al-Kutayfah." He said: And my brother Umayr was killed. So I brought the sword to the Prophet, may Allah bless him and grant him peace. He said: "Go and throw it into the collection." I returned, and only Allah knew the grief I felt regarding the killing of my brother and the taking of my sword. I had waited only a little while when Surah al-Anfal was revealed. The Messenger of Allah, may Allah bless him and grant him peace, called me and said: "Go and take your sword."