5-52 (The compiler of the book narrated) that his father - may God be pleased with him - narrated that Muhammad ibn Yahya al-Attar quoted Ahmad ibn Muhammad ibn Isa, on the authority of Al-Hassan ibn Mahboob, on the authority of Am’mar ibn Marvan,

“I heard Aba Abdullah as-Sadiq (MGB) say, ‘There is one-fifth levy on what is extracted from mines and the sea; on booties; on what is illegally obtained and is mixed with what is legally earned and no one knows its owner; and on treasures.”