The Sama Veda focuses on the musical chanting patterns of the [[w:Mantra|Mantras and the subtle form of Yajna by defining the latter as the process of mental oblation on the surface of internal emotions through the cosmic radiation of the omnipresent subtle energy of sound .
Sama Veda is recited while performing a yagna.
Rigveda is the Veda of knowledge , Yajurveda is the Veda of Karma , Sama Veda is the Veda of Bhakthi and Atharva Veda is Brahma-Veda, an umbrella celebrating the Divine Presence.
Sage Vyasa is known as Veda Vyasa, as he classified and compiled together, the vast body of Vedas or mantras then existing. He classified the Vedas in four, namely Rig , Yajur, Sama and Atharvana and taught them respectively to four great Rishis – Sumantu, Vaisampayana, Jaimini and Paila.
After gradual research; I have come to the conclusion that long before all heavenly books, God had revealed to the Hindus, through the Rishis of yore, of whom Brahma was the Chief, His four books of knowledge, the Rig Veda, the Yajur Veda, the Sama Veda and the Atharva Veda. The Quran itself made veiled references to the Upanishads as the first heavenly book and the fountainhead of the ocean of monotheism.