It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The wound caused by an animal is without liability, the well is without liability, the mine is also without liability, and in rikaz (buried treasure) there is khums."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7645
It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The wound caused by an animal is without liability (there is no penalty on the owner), the well is without liability, the mine is without liability, and in rikaz (buried treasure) there is khums."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7647
Amr bin Shu'ayb narrates from his father, and he from his grandfather (may Allah be pleased with him), that the Prophet (peace and blessings be upon him) said concerning a kanz (treasure) which people obtain from old ruined houses: "If it was found in an inhabited house or on a frequented road, then let it be announced; and if he obtained it from an old ruin of the Jahiliyyah or from an uninhabited village, then in it and in rikaz there is khums."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7648
Sayyiduna Anas bin Malik (may Allah be pleased with him) said: We were with the Messenger of Allah (peace and blessings be upon him), and a companion of ours entered a ruined place to relieve himself, and he saw a nugget of gold. He brought it to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Weigh it." It was weighed and it was two hundred dirhams, so the Messenger of Allah (peace and blessings be upon him) said: "This is rikaz; there is khums in it."
Abd al-Rahman bin Zayd bin Aslam is da'if (weak).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7649
Ibn Bukayr (may Allah have mercy on him) narrates from Imam Malik (may Allah have mercy on him) that he heard some scholars say: "Rikaz is the buried treasure of the Jahiliyyah which has not been sought by spending wealth, and for which no great labour has been undertaken. But whatever is sought by spending wealth, or for which great labour is undertaken, so that sometimes it is found and sometimes it is missed, that is not rikaz."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7650