(40) باب مَا جَاءَ فِي الرِّكَازِ وَمَا فِيهِ
Al hasan said "Rikaz means treasure buried in pre Islamic times."
Reference: Sunan Abi Dawud 3086
In-book reference: Book 20, Hadith 159
English translation: Book 19, Hadith 3080