說無垢稱經疏 3.321

3.321

贊曰：自下第六，命大剪剃男，初命、後詞。此命也。摩訶大也。迦多衍者，此云剪剃，婆羅門法諱為剃剪，時為不淨，以顯垢膩污淨行故。昔有多仙久居山野，髮鬢繁長無人為剪。時有一仙，舊有二子，俱來覩父。大者恥污，不肯為剪；小者慈孝，為父剪髮鬚，而乃為法仙剃之，多仙因此還得剪剃。為剪剃者，諸仙護念，初大富貴，後亦成仙。因以為姓，今是彼種，故言剪剃。具足威神，簡餘小者，故立大名。那者男聲，其父及身俱是彼種，以男聲詮，簡別云也，西方亦有取母姓故。如滿慈子母，婆羅門姓彌勒故，隨其父母好姓便取。

Commentary: From here below is the sixth, commanding the Great Shaving-Son (Mahākātyāyana); first the command, and second the words. This is the command. 'Mahā' means great. 'Kātyāyana': here rendered 'shaving' (kaṭa/kātya). In the brahmin custom, it was taboo to shave, and at the time it was considered impure, because it was seen as grime and oil defiling pure conduct. In antiquity, many ṛṣis lived for a long time in the mountains and wilds; their hair and whiskers grew long and thick, and there was no one to trim them. At that time, there was an ṛṣi who formerly had two sons, both of whom came to see their father. The elder was ashamed of the defilement and was unwilling to trim them; the younger was compassionate and filial, trimming the hair and beard for his father, and so he shaved it for the Dharma ṛṣi. Due to this, the many ṛṣis were also able to be shaved. For shaving them, he was protected and remembered by the many ṛṣis; at first he attained great wealth and nobility, and later he also became an ṛṣi. This became his clan name; now, being of that lineage, he is called 'Shaving' (Kātyāyana). Possessing complete majesty and spiritual power, and distinguishing him from other lesser ones, he was given the designation 'Great' (Mahā-). 'Na' is the masculine ending; his father and he himself were both of that lineage. Explained with the masculine ending, it makes a distinction, for in the Western regions there are also those who take the mother's clan name. Like Pūrṇamaitrāyaṇīputra, whose mother was of the brahmin Maitreya clan, they take whichever parent has the good clan name.