Cleanliness is essential for making advancement in spiritual life. There are two kinds of cleanliness: external and internal. External cleanliness means taking a bath, but for internal cleanliness one has to think of Krishna always and chant Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare. This process cleans the accumulated dust of past karma from the mind.
Bhagavad Gita 13.8-12,
You just accept the holy name, then Nityananda Prabhu will be responsible for taking you across this material world.
Any person who is chanting the holy names of Krishna (Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare) in course of chanting without offenses feels some transcendental pleasure and very quickly becomes puriﬁed of all material contamination.
Bhagavat Gita 9.2,
Caitanya Mahaprabhu has recommended that everyone chant the Hare Krishna mantra just to cleanse the dust from the heart. If the dust of the heart is cleansed away, then one can actually understand the importance of the holy name.
Nectar of Devotion, Chapter 12,
One need only chant the Hare Krishna mahamantra. Everyone engaged in the practice of chanting the Hare Krishna mahamantra will be completely cleansed, from the core of his heart, and be saved from the cycle of birth and death.
Srimad Bhagavatam 7.6.1,
The Hare Krishna mahamantra is also a prayer, for a prayer addresses the Supreme Personality of Godhead by His name and invokes good fortune by petitioning the Lord to allow one to engage in His devotional service.
Srimad Bhagavatam 4.24.69,