What is intended by it is that the one-fifth levy (khums) is not established by the apparent wording of the Quran except specifically in spoils, because whatever is other than the spoils in which we have made the one-fifth levy (khums) obligatory, all of that is only established by the Sunnah. And the Imam عليه السلام, peace be upon him, did not mean that there is no one-fifth levy (khums) in it in every circumstance.
Commentary #2