The Chandogya Upanishad belongs to the Sama Veda. Chandoga is the singer of the Saman (1). The Upanishads that belongs to the followers of the Sama Veda is the Chandogya Upanishad. It is part of the Chandogya Brahmana which has ten chapters. The first two chapters of the Brahmana deal with sacrifices and other forms of worships. The other eight constitutes the Chandogya Upanishad.

The first and the second chapters discuss the problems of liturgy and doctrine such as the genesis and significance of Aum and the meaning and names of Saman.

chando sama gayati iti chandogah

Source S. Radhakrishnan : The Principal Upanishads