梵網經菩薩戒本疏 3.6

3.6

三、次第者，若依《十善戒經》，婬但防邪，殺、盜不爾，故居後。此順彼位，而總斷為異。又釋：身業犯中，殺望前境，違惱最極，是故在初。盜違其次，婬違最劣，或順貪心，故在第三。問：若爾，何故聲聞戒中，此戒最初？答：婬欲為生死本，聲聞正為厭捨生死，速趣涅槃，故先制此。菩薩不爾，故在第三。又釋：彼戒是待犯方制之戒，婬最初犯，制匪後立。此戒既不待犯方制，故依古戒，順十善業，不同彼也。

Third, regarding the sequential order: according to the Sūtra on the Ten Good Precepts, sexual misconduct only guards against the improper [partners], whereas killing and stealing do not allow exceptions; hence it comes after them. This follows that sequence, yet differs in that it proscribes [all sexual activity] entirely. Another explanation: among transgressions of bodily action, killing causes the most extreme harm and distress toward the object; therefore it comes first. Stealing causes the next most harm, while sexual misconduct causes the least harm [to others] or merely accords with a greedy mind; thus it is placed third. Question: If so, why is this precept placed first among the śrāvaka precepts? Answer: Sexual desire is the root of saṃsāra, and the śrāvakas precisely seek to revile and abandon saṃsāra and swiftly proceed toward nirvāṇa; therefore this was instituted first [for them]. For bodhisattvas it is not so; thus it is third. Another explanation: their precepts were instituted only after an offense occurred, and sexual activity was the first offense committed, so the institution could not have been placed later. These [bodhisattva] precepts do not wait for an offense to be committed before being instituted; hence they rely on the ancient precepts and accord with the ten good actions, differing from those.