Teachings of the Hindu Mystics edited by Andrew Harvey contains many texts on the path of devotion. Here is a poem by the poet-saint Tukaram on devotion.
He who utters the Name of God while walking
gets the merit of a sacrifice at every step.
His body becomes a place of pilgrimage.
He who repeats God's Name while working
always find perfect peace.
He who utters the Name of God while eating
gets the merit of a fast
even though he has taken his meals.
Even if one were to give in charity
the whole earth encircled by the seas
it would not equal the merit of repeating the Name.
By the power of the Name
one will know what cannot be known,
One will see what cannot be seen,
One will speak what cannot be spoken,
One will meet what cannot be met.
Incalculable is the gain that comes
from repeating the Name of God."