It has been mentioned that paper is work and gold is knowledge, and zakat on work is obligatory for it, and zakat on knowledge is also obligatory for it, for voluntary deeds and sciences are many, and they are the ones that are subject to zakat as obligatory, because zakat is obligatory, and whatever voluntary charity is voluntary charity, it is the servant’s presence in that work from the initiation. In it, etc., there is another zakat, I mean voluntary zakat, which is that one intends by doing that to complete the obligatory duties .