It is narrated from Sayyiduna Anas bin Malik, may Allah be pleased with him, he says: We went towards Khaybar with the Messenger of Allah, peace and blessings be upon him. One of our companions went to a deserted place to relieve himself. When he picked up a brick to perform istinja, he found a gold nugget there. He picked it up and brought it to the Noble Prophet, peace and blessings be upon him, and told him the whole story. The Prophet, peace and blessings be upon him, said: Weigh it. He weighed it and it was two hundred dirhams. The Noble Prophet, peace and blessings be upon him, said: This is rikaz, and one-fifth (khumus) is due as zakat on it.