俱舍論記 17.155

17.155

「又彼父母至觸無間罪」者，釋第三句。若天生黃門，謂彼父、母於彼少恩，為彼缺身增上緣故，又由於彼少愛念故。若被損黃門，以身缺故，父、母於彼少愛念故。扇搋等，於彼父母慚愧心微，以無現前增上慚、愧可言壞故，觸無間罪。問：若天生黃門可慚愧微，父母恩少缺身緣故。被損黃門，父母於彼非缺身緣，如何於父母慚愧心微？解云：父母於彼少愛念故，所以彼於父母慚愧心微。

Regarding "Furthermore, because those parents ... incurs the uninterrupted sin": this explains the third line. In the case of one born as a eunuch, their parents have little kindness toward them, serving as the predominant condition for their deficient body, and also because they harbor little affectionate love for them. In the case of one who has been made a eunuch by injury, because their body is deficient, the parents harbor little affectionate love for them. Ṣaṇḍhas and the like possess only feeble shame and conscience toward their parents; because they have no present, predominant shame and conscience that could be said to be destroyed, they incur no uninterrupted sin. Question: If one born as a eunuch may have feeble shame and conscience because their parents' kindness is slight due to being the condition for their deficient body, in the case of one injured into becoming a eunuch, the parents were not the condition for the deficiency of their body—how then is their shame and conscience toward their parents feeble? The explanation says: because the parents harbor little affectionate love for them, their shame and conscience toward their parents are feeble.