Among Amritdhari Sikhs, a few texts from Dasam Granth which are read as Nitnem, like Tav-Prasad Savaiye and Chaupai, are also considered Gurbani.
In Adi Granth, Gurbani is a sound which comes directly from the Supreme and the text is a written form of the same in worldly language and scripts.
[1] Prior to reading Gurbani or meditating, it is compulsory to cover the head with a turban, dupatta or other cloth, as well as removing shoes, performing at least the Panj Ishnan[2] (washing of the 5 main parts of the body), and if possible using a teeth-cleaning twig.
[3] Gurbani are explanations of qualities of the Primal Lord and Soul which a Sikh should comprehend and with which they can attain the supreme state.
Gurbani is directly received from inside after attaining a Supreme state, whereas the Granth or textual form is worldly language of the same.
Gurbani is not seen as mere intellectual, spiritual writings conjured by the Sikh gurus, bhagats, bhatts, and gursikhs, but rather as divine word revealed by the creator itself.