梵網經菩薩戒本疏 1.43

1.43

第二、次第者，戒相塵沙無邊浩污，何故最初辨茲殺戒？一、謂菩薩萬行無不以大悲為本，為存行本故先制也；二、有情所重莫不以形命為先，為救物命故先辨也。若爾，何故聲聞戒初不同此耶？謂此以救生行為先，彼以自行為首。又釋：彼要待犯已方制，婬戒初犯，故殺不先。《僧祇律》云：成道五年制婬，第六年制盜及殺。菩薩不爾，約十業道此為初故，三世本戒非新制故。

Second, the sequence: The marks of the precepts are as boundless and vast as the dust and sands; why is this precept against killing analyzed first? First, all the myriad practices of a bodhisattva take great compassion as their root; in order to preserve the root of practice, it is proscribed first. Second, among what sentient beings value, nothing comes before physical life; in order to save the lives of beings, it is analyzed first. If so, why is the beginning of the śrāvaka precepts not like this? Because this [bodhisattva vinaya] takes the practice of saving life as primary, whereas that [śrāvaka vinaya] takes one's own practice as foremost. Another explanation: that [vinaya] had to wait for a violation to occur before being proscribed, and the precept against sexual misconduct was violated first, so killing was not first. The Mahāsāṃghika-vinaya states: In the fifth year after attaining awakening, sexual misconduct was proscribed; in the sixth year, stealing and killing were proscribed. For bodhisattvas it is not so: in terms of the ten karmic paths, this is the first, and because it is the fundamental precept of the three periods, it is not newly proscribed.