Śatapatha Brāhmaṇa ("of a hundred paths") 11.2.6.10

11.2.6.10

tā ekaviṃśatirāhutayaḥ dvāvāghārau pañca prayājā dvāvājyabhāgāvāgneyaḥ puroḍāśastaddaśāgnīṣomīya upāṃśuyājo'gnīśomīyaḥ puroḍāśo'gniḥ sviṣṭakṛdiḍā trayo'nuyājāḥ sūktavākaśca śamyorvākaścātha yadevādaḥ patnīsaṃyājeṣu sampragṛhṇāti samiṣṭayajuśca

These are twenty-one offerings;--two libations of ghee, five fore-offerings, two butter-portions, and Agni's cake: this makes ten; Agni and Soma's low-voiced offering, Agni and Soma's cake, the Agni Svishtakrit, the Idâ, three after-offerings, the Sûktavâka, the Samyorvâka, further his seizing (the two spoons) at the same time there at the Patnîsamyâgas and (last) the Samishtayagus.