Śatapatha Brāhmaṇa ("of a hundred paths") 13.8.2.5

13.8.2.5

atha dakṣiṇataḥ sīram yunakti uttarata ityu haika āhuḥ sa yathā kāmayeta tathā kuryādyuṅkteti sampreṣyābhimantrayate savitā te śarīrebhyaḥ pṛthivyāṃ lokamicatviti savitaivāsyaitacarīrebhyaḥ pṛthivyāṃ lokamicati tasmai yujyantāmusriyā ityetasmā u hi karmaṇa usriyā yujyante

He (the Adhvaryu) then yokes (the team) to the plough on the south side,--some say on the north side: he may do as he chooses. Having given the order, saying, 'Yoke!' he (the Sacrificer) utters the formula (Vâg. S. XXXV, 2), 'May Savitri vouchsafe for thy bones a place in the earth!'--Savitri now indeed vouchsafes a place in the earth for his (the deceased man's) bones;--'Let the oxen be yoked therefore!' for it is indeed for this work that the oxen are yoked.