Shatapatha Brahmana 5.1.5.17

5.1.5.17

athaitābhyāṃ jagatībhyām | juhoti vānu vā mantrayate yadi juhoti yadyanumantrayate samāna eva bandhuḥ

And if a pupil of the Adhvaryu's or some (other) theological student were to know that prayer, stepping up he makes (the Sacrificer) say, 'O coursers!'--for horses are indeed coursers: therefore he says, 'O coursers'--'wealth-winners!' for wealth is food: 'food-winners' he thereby says;--'keeping the roads,' for they indeed run keeping (within) the roads;--'measuring the stages;' for measuring the stages they run over the course;--'go ye to the winning-post!' In order that the evil-doers, the Rakshas, may not hurt them midways, he thus says this.--They run the race, they beat the drums, and he (the Brahman) sings the Sâman.