Śatapatha Brāhmaṇa ("of a hundred paths") 5.3.5.2

5.3.5.2

agṛhīte māhendre | eṣa vā indrasya niṣkevalyo graho yanmāhendro 'pyasyaitanniṣkevalyameva stotraṃ niṣkevalyaṃ śastramindro vai yajamānastadenaṃ sva evāyatane 'bhiṣiñcati tasmādagṛhīte māhendre

Before the Mâhendra (cup) has been drawn,--for that Mâhendra cup is Indra's special (nishkevalya) cup, and so is that Nishkevalya Stotra (hymn) and Nishkevalya Sastra (recitation); and the Sacrificer is Indra: he thus consecrates him--in his own resting-place. Hence before the Mâhendra (cup) has been drawn,--