Shatapatha Brahmana 10.5.1.3

10.5.1.3

so'yamātmā tredhāvihita eva so'nena tredhāvihitenātmanaitaṃ tredhāvihitaṃ daivamamṛtamāpnoti tā u sarvā iṣṭakā ityevācakṣate neṣṭaka iti neṣṭakamiti vāco rūpeṇa vāgghyevaitatsarvaṃ yatstrī punānnapuṃsakaṃ vācā hyevaitatsarvamāptaṃ tasmādenā aṅgirasvaddhruvā sīdetyeva sarvāḥ sādayati nāṅgirasvaddhruvaḥ sīdeti nāṅgirasvaddhruvaṃ sīdeti vācaṃ hyevaitāṃ saṃskurute

This body (of the altar), indeed, is threefold; and with this threefold body he obtains the threefold divine Amrita (nectar, immortality). Now all these (bricks) are called 'ishtakâ (f.),' not 'ishtakah (m.),' nor 'ishtakam (n.):' thus (they are called) after the form of speech (vâk, f.), for everything here is speech--whether feminine (female), masculine (male), or neuter--for by speech everything here is obtained. Therefore he 'settles' all (the bricks) with, 'Aṅgiras-like lie thou steady (dhruvâ, f.)!' not with, 'Aṅgiras-like lie thou steady (dhruvah, m.)!' or with, 'Aṅgiras-like lie thou steady (dhruvam, n.)!' for it is that Speech he is constructing.