Śatapatha Brāhmaṇa ("of a hundred paths") 4.2.4.1

4.2.4.1

ayaṃ ha vā asyaiṣa prāṇaḥ | yo 'yam purastātsa vai vaiśvānara evātha yo 'yam paścātsa dhruvastau ha smaitau dvāvevāgre grahau gṛhṇanti dhruvavaiśvānarāviti tayorayamapyetarhyanyatara eva gṛhyate dhruva eva sa yadi taṃ carakebhyo vā yato vānubruvīta yajamānasya taṃ camase 'vanayedathaitameva hotṛcamase

That (opening of) vital air of his which is in front, that, forsooth, is the Vaisvânara (graha); and that which is behind is the Dhruva. Formerly, indeed, both these grahas, the Dhruva and Vaisvânara, were drawn; and even now one of them is still drawn, to wit, the Dhruva. And if he acquire a knowledge of that (Vaisvânara graha) either from the Karakas, or from anywhere else, let him pour it into the sacrificer's cup; but this (Dhruva graha he pours) into the Hotri's cup.