瑜伽師地論略纂 3.134

3.134

別釋九句中，初七句名加行殺害，勵力殺故；次一句名無擇殺害，逢生即殺，不簡釋故；後之一句名殺生時，從初斷命，未遇良緣受持戒等，常成殺生業道罪故。

In the separate explanation of the nine phrases: the first seven phrases are called preparatory killing, because one kills with exertion; the next phrase is called killing without discrimination, because one kills whenever encountering living beings without selecting or sparing them; the final phrase is called the time of killing, because from the initial severance of life, if one has not encountered good conditions to uphold precepts and the like, it constantly constitutes the transgression of the path of karma of killing living beings.