Śatapatha Brāhmaṇa ("of a hundred paths") 11.3.2

11.3.2.1

yo ha vā agnihotre ṣaṇmithunāni veda mithunena-mithunena ha prajāyate sarvābhiḥ prajātibhiryajamānaśca patnī ca tadekam mithunaṃ tasmādasya patnīvadagnihotraṃ syādetanmithunamupāpnavānīti vatsaścāgnihotrī ca tadekam mithunaṃ tasmādasya puṃvatsāgnihotrī syādetanmithunamupāpnavānīti sthālī cāṅgārāśca tadekam mithunaṃ srukca sruvaśca tadekam mithunamāhavanīyaśca samicca tadekam mithunamāhutiśca svāhākāraśca tadekam mithunametāni ha vā agnihotre ṣaṇmithunāni tāni ya evaṃ veda mithunena-mithunena ha prajāyate sarvābhiḥ prajātibhiḥ

Verily, whosoever knows the six pairs in the Agnihotra, has offspring born to him by pair after pair, by all generations. The Sacrificer and his wife--this is one pair: through it his Agnihotra would be possessed of a wife,--'May I obtain this pair!' he thinks. The calf and the Agnihotra-cow--this is another pair: through it his Agnihotra-cow would become possessed of a male calf,--'May I obtain this pair!' he thinks. The pot and the coals--this is another pair; the offering-spoon and the dipping-spoon--this is another pair; the Âhavanîya fire and the log--this is another pair; the libation and the Svâhâ-call--this is another pair: these, doubtless, are the six pairs in the Agnihotra; and he who thus knows them, has offspring born to him by pair after pair, by all generations.