法苑珠林 68.44

68.44

問曰。何故名故心者。答曰。若不故心成殺生罪者。則阿羅漢不得涅槃。以阿羅漢斷世間因。有不作心而殺眾生。亦應還生世間。而實不然。以是義故。不故心殺不得罪報。

Question: Why is it named 'intentional mind'? Answer: If without an intentional mind the sin of killing living beings were constituted, then an arhat would not attain nirvāṇa. Because an arhat has cut off worldly causes, if he were to kill a sentient being without an acting mind, he should also be reborn in the world; but in fact that is not so. By this meaning, killing without an intentional mind does not incur sinful retribution.