Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.2.4

2.3.2.4

teṣāmupasthānam | yadeva sāyam prātarāhavanīyamupa ca tiṣṭhata upa cāste tadeva tasyopasthānamatha yadeva pratiparetya gārhapatyamāste vā śete vā tadeva tasyopasthānamatha yatraiva saṃvrajannanvāhāryapacanamupasmarettadeva tam manasopatiṣṭheta tadeva tasyopasthānam

Now as to rendering homage to (upasthâna, lit. standing near) these (fires). When in the evening and morning (after the Agnihotra) he stands by the Âhavanîya, and sits down by it, that is the homage rendered to that (fire). And when, on stepping back to the Gârhapatya, he either sits or lies down, that is the homage rendered to that (fire). And when, in walking (out of the sacrificial ground), he remembers the Anvâhâryapakana, and thus, in his mind, tarries near it, that is the homage rendered to that (fire).