The Compendium of Caraka 4.8.44_1

4.8.44_1

atastasyāḥ kalpanavidhimupadekṣyāmaḥ---nābhibandhanāt prabhṛtyaṣṭāṅgulamabhijñānaṃ kṛtvā chedanāvakāśasya dvayorantarayoḥ śanairgṛhītvā tīkṣṇena raukmarājatāyasānāṃ chedanānāmanyatamena-ārdhadhāreṇa chedayet/

Now we shall teach the rule for cutting it: having made a mark at eight finger-breadths from the navel attachment, holding gently at both intervals of the cutting place, one should cut it with a sharp, semi-bladed instrument of gold, silver, or iron.