Hadith 5:973
Hushaym narrated to us, from Husayn, from someone who witnessed [the Battle of] al-Qadisiyyah: While a man was bathing, the water uncovered for him a brick of gold from the dirt. He came to Sa’d ibn Abi Waqqas and informed him. He [Sa’d] said: "Place it among the spoils of the Muslims."
حدثنا هشيم عن حصين عمن شهد القادسية بينما رجل يغتسل إذ فحص له الماء التراب عن لبنة من ذهب فأتى سعد بن أبي وقاص فأخبره فقال اجعلها في غنائم المسلمين