梵網經菩薩戒本疏 6.3

6.3

初、制意者，本為受行大乘名為菩薩，今若捨此何大士之有？別說亦三：一、乖大行；二、習異熏心；三、障得菩提。為失既深，故須制也。

First, the intention of the regulation: Fundamentally, it is because of receiving and practicing the Mahāyāna that one is called a bodhisattva; if one now abandons this, how can there be a great being? The distinct explanation also has three points: 1. Contravening great practice; 2. Practicing heterodoxies and perfuming the mind; 3. Obstructing the attainment of bodhi. Because the loss is profound, it must be prohibited.