Paraskaragrihyasutra 2.1.11

2.1.11

śivo nāmeti lohakṣuramādāya nivartayāmīti pravapati yenāvapatsavitā kṣureṇa somasya rājño varuṇasya vidvān \ tena brahmāṇo vapatedamasyāyuṣyañjaradaṣṭiryathāsaditi \11\

Taking up a copper razor with (the formula), 'Friendly by name' (Vâg. Samh. III, 63 a), he cuts (the hair) with (the formula), 'I cut off' (ibid. 63b), (and with the formula,) 'The razor with which Savitri, the knowing one, has shaven (the beard) of king Soma and Varuna, with that, ye Brâhmanas, shave his (head), in order that he may be blessed with long life and may reach old age.'