The Sanskrit word bhajan or bhajana is derived from the root bhaj, which means “divide, share, partake, participate, to belong to”. The word also connotes “attachment, devotion to, fondness for, homage, faith or love, worship, piety to something as a spiritual, religious principle or means of salvation”.

In Hinduism, Bhajan and it’s Bhakti analog Kirtan, have roots in the ancient metric and musical traditions of the Vedic era, particularly the Samaveda. The Samaveda Samhita is not meant to be read as a text, it is like a musical score sheet that must be heard.

Other late Vedic texts mention the two scholars Shilalin (IAST: Śilālin) and Krishashva (Kṛśaśva), credited to be pioneers in the studies of ancient drama, singing, and dance. The art schools of Shilalin and Krishashva may have been associated with the performance of Vedic rituals, which involved storytelling with embedded ethical values.[11] The Vedic traditions integrated rituals with performance arts, such as a dramatic play, where not only praises to gods were recited or sung, but the dialogues were part of a dramatic representation and discussion of spiritual themes.

A lyric from a Hindu Bhajan

This body is but a guest of four days,
a house made of dirt.
On this earth, your mark is made,
a symbol of your good work.

— Translated by David N. Lorenzen

The Vedas and Upanishads celebrate Nada-Brahman, where certain sounds are considered elemental, triggering emotional feelings without necessarily having a literal meaning, and this is deemed sacred, the liminal experience of the primeval ultimate reality and supreme truth. This supreme truth is, states Guy Beck, considered as full of bliss and rasa (emotional taste) in the Hindu thought, and melodic sound considered a part of the human spiritual experience. Devotional music genre such as Bhajan is part of a tradition that emerged from these roots

Source: Wikipedia