It is narrated from Ibn Abbas (may Allah be pleased with them both) that on the day of Badr the Messenger of Allah (peace and blessings be upon him) took his sword Dhu al-Fiqar as an extra share (nafl) from the spoils.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12750