Shankhayanagrihyasutra 2.13.6

2.13.6

: medhya amedhya vibhāgajñe devi goptri sarasvati.|.mekhale askannam achinnam saṃtanuṣva vratam mama tvam agne vratabhṛt śucir agne devān iha āvaha.|.upa yajñam haviś ca naḥ vratāni bibhrad vratapā adābhyo bhavā no dūto ajaraḥ suvīraḥ.|.dadhad ratnāni sumṛlīko agne gopāya no jīvase jāta veda iti /

And he ties the sacrificial cord to the staff.