Śatapatha Brāhmaṇa ("of a hundred paths") 13.1.2.4

13.1.2.4

īśvaro vā eṣaḥ ārtimārtoryo brahmaṇe devebhyo'pratiprocyāśvaṃ badhnāti brahmannaśvam bhantsyāmi devebhyaḥ prajāpataye tena rādhyāsamiti brahmāṇamāmantrayate brahmaṇa evainam pratiprocya badhnāti nārtimārcati taṃ badhāna devebhyaḥ prajāpataye tena rādhnuhīti brahmā prasauti svayaivainaṃ devatayā samardhayatyatha prokṣatyasāveva bandhuḥ

But, verily, he who fetters the horse without announcing it to the Brahman and the gods is liable to incur injury. He addresses the Brahman (the superintending priest) by saying, 'O Brahman, I will fetter the horse for the gods, for Pragâpati: may I prosper therewith!' and having made the announcement to the Brahman, he ties up the horse, and thus incurs no injury. 'Fetter it for the gods, for Pragâpati: prosper thou therewith!' thus the Brahman urges him, and supplies it (the horse) with its own deity. He then sprinkles it (with water): the (symbolic) meaning of this is the same as before.