Hiranyakeshigrihyasutra 1.6.19.8

1.6.19.8

imaṃ me varuṇa \ tattvā yāmi \ tvaṃ no agne \ sa tvaṃ no agne \ tvamagne ayāsi \ prajāpate \ iti hutvāśmānamāsthāpayati \ ātiṣṭhemamaśmānamaśmeva tvaṃ sthirā bhava \ pramṛṇīhi durasyūnsahasva pṛtanāyataḥ \ iti \8\

After he has sacrificed with (the verses), 'This, O Varuna,' 'For this I entreat thee,' 'Thou Agni,' Thus thou, Agni,' 'Thou, Agni, art quick,' 'Pragâpati'—he makes her tread on a stone, with (the verse), 'Tread on this stone; like a stone be firm. Destroy those who seek to do thee harm; overcome thy enemies.'