俱舍論記 18.53

18.53

「要以殺心至無間則無」者，答。要以殺心出佛身血方成逆罪。打心出血，以罪輕故，無間則無。

Regarding "It requires an intention to kill [...] then an anantarya is absent": this is the answer. It requires an intention to kill that sheds the Buddha's blood for it to constitute an anantarya offense. If one sheds blood with an intention merely to strike, because the offense is minor, an anantarya is absent.