Śatapatha Brāhmaṇa ("of a hundred paths") 4.4.1.8

4.4.1.8

athābhakṣitena pātreṇa | vaiśvadevaṃ grahaṃ gṛhṇāti tadyadabhakṣitena pātreṇa vaiśvadevaṃ grahaṃ gṛhṇāti na vai sāvitrasyānuvaṣaṭkarotyetasmādvai vaiśvadevaṃ grahaṃ grahīṣyanbhavati tadasya vaiśvadevenaivānuvaṣaṭkṛto bhavati

Then with the (same) vessel, without drinking therefrom, he draws the Vaisvadeva graha. The reason why he draws the Vaisvadeva graha with the (same) vessel, without drinking therefrom, is this: on the Sâvitra graha he (the Hotri) pronounces no Anuvashat, and it is therefrom that he is about to draw the Vaisvadeva graha,--thus it is by means of the Vaisvadeva that it becomes supplied with the Anuvashat for him.