Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 10.6.21

10.6.21

tasmād āpryo nāma / (paśu: paśau prayāja anuyājāh)

called Āprīs (fillers). He surrounds the animal with fire, to smite away the Rakṣases; Agni is the smiter away of the Rakṣases; he carries the fire round thrice from left to right; that is as if Agni were to put three forts. Therefore, ‘Go round again’ he should say to the Agnīdh, if he desire of a man, ‘May he not fall away.’