妙法蓮華經玄義 7.33

7.33

第四觀心者，小乘明心起，未動身口，不名為業。大乘明剎那造罪，殃墜無間。無間是大苦報處，剎那促起業處。促心暫起，重業已成，況九法界而不具足。若能淨心，諸業即淨。

Fourth, regarding contemplation of mind: the Hīnayāna explains that when a thought arises in the mind, as long as body and speech have not moved, it is not called karma. The Mahāyāna explains that creating sin in a single kṣaṇa brings retribution that plunges one into the Avīci [hell]. Avīci is a place of great suffering retribution; a kṣaṇa is the locus where karma is precipitously generated. When a precipitous thought briefly arises, heavy karma is already formed; how much more so are the nine dharma realms fully present! If one can purify the mind, all karmas are immediately purified.