Śatapatha Brāhmaṇa ("of a hundred paths") 13.2.2.15

13.2.2.15

taddhaike eteṣām paryaṅgyāṇāṃ nānā yājyāpuro'nuvākyāḥ kurvanti vindāma eteṣāmavittyetareṣāṃ na kurma iti na tathā kuryātkṣatraṃ vā aśvo viḍitare paśavaḥ pratipratinīṃ ha te pratyudyāminīṃ kṣatrāya viśaṃ kurvantyatho āyuṣā yajamānaṃ vyardhayanti ye tathā kurvanti tasmātprājāpatya evāśvo devadevatyā itare kṣatrāyaiva tadviśaṃ kṛtā?ukarāmanuvartmānaṃ karotyatho āyuṣaiva yajamānaṃ samardhayati

Now some make the invitatory-formulas and the offering-formulas (to be pronounced) separately for the 'paryaṅgyas,' saying, 'For these we find (formulas)--for the others, on account of not finding any, we do not use them.' Let him not do so; for the horse is the nobility (chieftain), and the other animals are the peasantry (clan); and those who do this really make the peasantry equal and refractory to the nobility; and they also deprive the Sacrificer of his vital power. Therefore the horse alone belongs to Pragâpati, and the others are sacred to the gods: he thus, indeed, makes the peasantry obedient and subservient to the nobility; and he also supplies the Sacrificer with vital power.