Srimad-Bhagavatam: Canto 5 - Chapter 1 - Verse 16

Sanskrit:

पुरस्तात्सवितुररुण: पश्चाच्च नियुक्त: सौत्ये कर्मणि किलास्ते ॥ १६ ॥

ITRANS:

purastāt savitur aruṇaḥ paścāc ca niyuktaḥ sautye karmaṇi kilāste.

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