Surya Siddhanta
हिरण्यगर्भो भगवान् एष छन्दसि पठ्यते। आदित्यो ह्य् आदिभूतत्वात् प्रसूत्या सूर्य उच्यते॥
He is described in the Vedas as hiraëyagarbha [He in the scripture (chandas) is denominated the golden-wombed (hiranyagarbha) ]. Because He was there at the beginning (ädi), He is called Äditya and because He is the creator, He is called the sun (Sürya).
english translation