MANTRA OR ZIKR
A mantra is very beneficial to a neophyte on the spiritual path, particularly so when it is given by the guru. The first and immediate result accruing from frequent repetition of a
word or words is the concentration of the mind on the subject to be gained.
Secondly, the sound vibrations as a result of continuous repetition induce, in the course of time, harmonious sympathy to the sound vibrations of the higher planes, engendering a blissful feeling -- a factor greatly encouraging to a beginner.
This blissful feeling, coupled with the awakening of mental powers, is called the Mantric force, and it has immense possibilities for good as well as bad.
(Treasures-p. 190, ed. Jane B. Haynes)