In the earliest days of Buddhism monks were required to devote all their efforts to their religious vocation once the four basic needs (food, clothing, bedding and medicine) had been met. If one lives a simple life, then one's karma will prosper.
所以原始佛教的精神是四事（飲食、衣服、臥具、醫藥﹚供養具足之後，就得安心於道上用功，生活簡樸道業興隆。