Srimad Bhagavatham 6:2:10
सर्वेषाम् अप्य् अघवताम् इदम् एव सुनिष्कृतम्
नाम-व्याहरणं विष्णोर् यतस् तद्-विषया मतिः
sarvesam apy aghavatam idam eva suniskrtam
nama vyaharanam visnor yatas tad-visaya matih
Simply by chanting the holy name of Lord Vishnu, such persons may attract the attention of the Supreme Lord, who therefore considers, “Because this man has chanted My holy name, My duty is to give him protection.”
According to Lakshmidara Kavi, the pioneer of the Nama Siddhanta tradition, the potency of the Nama Sankeerthanam can be traced to the Rig Vedas.
”Asya jananto nama cidvivaktana
mahaste visno sumatim bhajamahe“
By Chanting the Divine Names of Lord Vishnu one can attain the supreme knowledge.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji