Ramayana
तमेव कालं मित्रो ऽपि वरुणत्वमकारयत् । क्षीरोदेन सहोपेतः पूज्यमानः सुरोत्तमैः ॥ 7-56-12 ॥
At that very time Mitra too had assumed the office of Varuna, dwelling together with the Ocean of Milk and worshipped by the foremost of the gods.
english translation