SB 6.2.11

na niṣkṛtair uditair brahma-vādibhis
 tathā viśuddhyaty aghavān vratādibhiḥ
yathā harer nāma-padair udāhṛtais
 tad uttamaśloka-guṇopalambhakam
Word for word: 
na — not; niṣkṛtaiḥ — by the processes of atonement; uditaiḥ — prescribed; brahma-vādibhiḥ — by learned scholars such as Manu; tathā — to that extent; viśuddhyati — becomes purified; agha-vān — a sinful man; vrata-ādibhiḥ — by observing the vows and regulative principles; yathā — as; hareḥ — of Lord Hari; nāma-padaiḥ — by the syllables of the holy name; udāhṛtaiḥ — chanted; tat — that; uttamaśloka — of the Supreme Personality of Godhead; guṇa — of the transcendental qualities; upalambhakam — reminding one.
Translation: 
By following the Vedic ritualistic ceremonies or undergoing atonement, sinful men do not become as purified as by chanting once the holy name of Lord Hari. Although ritualistic atonement may free one from sinful reactions, it does not awaken devotional service, unlike the chanting of the Lord’s names, which reminds one of the Lord’s fame, qualities, attributes, pastimes and paraphernalia.
Purport: 

Śrīla Viśvanātha Cakravartī Ṭhākura comments that the chanting of the holy name of the Lord has special significance that distinguishes it from the Vedic ritualistic ceremonies of atonement for severe, more severe or most severe sinful actions. There are twenty types of religious scriptures called dharma-śāstras, beginning with the Manu-saṁhitā and Parāśara-saṁhitā, but herein it is stressed that although one may become free from the reactions of the most sinful activities by following the religious principles of these scriptures, this cannot promote a sinful man to the stage of loving service to the Lord. On the other hand, chanting the holy name of the Lord even once not only frees one immediately from the reactions of the greatest sins, but also raises one to the platform of rendering loving service to the Supreme Personality of Godhead, who is described as uttamaśloka because He is famous for His glorious activities. Thus one serves the Lord by remembering His form, His attributes and pastimes. Śrīla Viśvanātha Cakravartī Ṭhākura explains that this is all possible simply by chanting the Lord’s holy name because of the Lord’s omnipotence. What cannot be achieved through the performance of Vedic rituals can be easily achieved through the chanting of the Lord’s holy name. To chant the holy name and dance in ecstasy is so easy and sublime that one can achieve all the benefits of spiritual life simply by following this process. Therefore Śrī Caitanya Mahāprabhu declares, paraṁ vijayate śrī-kṛṣṇa-saṅkīrtanam: “All glories to Śrī Kṛṣṇa saṅkīrtana!” The saṅkīrtana movement we have started offers the best process for becoming purified of all sinful reactions and coming immediately to the platform of spiritual life.