Śatapatha Brāhmaṇa ("of a hundred paths") 13.5.2.22

13.5.2.22

sarvāptirvā eṣā vācaḥ yadbrahmodyaṃ sarve kāmā aśvamedhe sarvayā vācā sarvānkāmānāpnavāmeti

Verily, this is the complete attainment of speech, to wit the Brahmodya, and in the Asvamedha all desires are contained: 'By means of all speech may we obtain all our desires!' so (they think).