SB 5.21.16

purastāt savitur aruṇaḥ paścāc ca niyuktaḥ sautye karmaṇi kilāste.
Synonyms: 
purastāt — in front; savituḥ — of the sun-god; aruṇaḥ — the demigod named Aruṇa; paścāt — looking backward; ca — and; niyuktaḥ — engaged; sautye — of a charioteer; karmaṇi — in the work; kila — certainly; āste — remains.
Translation: 
Although Aruṇadeva sits in front of the sun-god and is engaged in driving the chariot and controlling the horses, he looks backward toward the sun-god.
Purport: 

In the Vāyu Purāṇa the position of the horses is described:

saptāśva-rūpa-cchandāṁsī
 vahante vāmato ravim
cakra-pakṣa-nibaddhāni
 cakre vākṣaḥ samāhitaḥ

Although Aruṇadeva is in the front seat, controlling the horses, he looks back toward the sun-god from his left side.