It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "One fifth shall be taken from rikaz (buried treasure)."

Imam Malik, may Allah have mercy on him, said: There is no difference of opinion in this matter according to us, and I have also heard from the people of knowledge that rikaz is a buried treasure from among the treasures of the disbelievers, when it is found without much effort and without spending money. So if it is found by spending money or with great effort, and sometimes it is found and sometimes not, then it will not be called rikaz.