On Japa-2:

By repeating the name of Krishna or Rama, a man transforms his physical body into a spiritual body - Sri Ramakrishna Paramahamsa

On Japa (Repetition of the Holy Name)-1:

People do not know what the Name of God can do. Those who repeat it constantly alone know its power. It can purify our mind completely. The Name can take us to the summit of spiritual experience - Swami Ramdas