俱舍論疏 15.68

15.68

論「有餘部說至苾芻律儀」，述經部計。言「墮罪」者，謂四重罪，墮地獄故，名為墮也。此說犯重亦捨戒故。

On the text "Other schools say … the bhikṣu restraint": this recounts the Sautrāntika doctrine. "Defeating offense" (pātayantikā/pārājika) refers to the four grave offenses: because one falls into hell, it is named "falling/defeating" (pāta). This states that committing a grave offense also abandons the precepts.