Vedas
There are numerous references to praising the Sun to enhance good health and prosperity, in the Vedas. Some of these Vedic hymns were incorporated into Nitya Vidhi (Daily mandatory routine for a Hindu). These daily procedures were termed Surya Namaskara (literally translates as "sun salutations"). The forms of Surya Namaskar practiced vary from region to region. Two such popular practices are Trucha Kapla Namaskarah and Aditya Prasna.
Puranas
Aditya Hridayam is another ancient practice which involves surya namaskar. It is a procedure of saluting The Sun, taught to Sri Rama by Sage Agastya, before his fight with Ravana. It is described in the "Yuddha Kaanda" Canto 107 of Ramayana.
Old English references
Early English publications record some of the ancient ways of sun salutation. In "A Catalogue raisonnée of oriental manuscripts",noted that a short book with 71 leaves with "Tricha calpa vidhi" from "Aditya Puranam" was preserved. He describes the vidhi as "Modes of rendering homage to Sun, with praise and spells; the object being health or delivery from disease". He further notes the presence of Arghya Pradana, Surya Stotaram, Aditya dvadasa namam - 12 names of the Sun according to the monthly signs of zodiac, Surya Narayana cavacham, Saurashtacshari mantram, and many other elaborate rituals as the part of the vidhi. In Page 148 of the same book he describes a shorter version called "Laghu tricha kalpa vidhi".
