俱舍論疏 18.33

18.33

論「逆罪亦成至謂父轉形」，明父、母轉根，殺亦成逆，依止一故。然父、母轉作畜生，殺不成逆。

The Śāstra states: "The anantarya offense is also constituted... meaning the father's form has changed", explaining that if the father or mother transforms their faculty, killing them still constitutes an anantarya, because the physical support (āśraya) is one. However, if the father or mother transforms into an animal, killing them does not constitute an anantarya.