梵網經菩薩戒本疏 6.176

6.176

初、制意者，菩薩理宜不惜身命護持淨戒，何容壞自本誓而無懼毀禁戒？故須嚴制。又為護一切戒品令堅固故，制此戒也。

First, concerning the intention of instituting the precept: a bodhisattva should in principle protect and uphold the pure precepts without sparing physical life; how can one permit ruining one's own fundamental vow and breaking the prohibitive precepts without fear? Therefore it had to be strictly instituted. Furthermore, in order to protect all categories of precepts and make them firm, this precept was instituted.