Nissaggiya 18 A monk is not to accept money. Buddhist monks are not allowed to accept money for themselves, nor are they permitted to tell a trustworthy layperson to receive it on their behalf and keep it for them (e.g. keeping a personal bank account). Such practices are explicitly prohibited by the 18th rule. If a monk accepts or receives gold or silver it must immediately be relinquished. This entails a pácittiya (usually a fault committed deliberately caused by letting oneself go - often owing to a lack of attention). Gold or silver includes all precious metals, coins, bank notes, cheques, credit cards, or all other monetary means enabling one to purchase or acquire something. The main reason the Buddha forbade a monk to possess money is stated in SN 42.10 where the Buddha said, " ... for whoever money is allowable, then for him the five sense pleasures are also allowable; for whoever the five sense pleasures are allowable, you can be certain he is not of the nature of a monk...." Nissaggiya 19 A monk is not to use money to buy and sell things for himself. If a monk uses gold or money or other monetary means to proceed in the exchange of anything whatsoever, he must abandon all that obtained by these means. This also entails a pácittiya. Nissaggiya 20 A monk is not to exchange things or barter. A monk may not barter directly with lay people and if a monk proceeds in an exchange, to a purchase or a sale, the object purchased in this way must be abandoned. This also entails a pácittiya.