Spiritual Master

But Dhruva was hardly five years of age. How could a five year old boy know anything about the observance of penance?

Narada came to know of it and appeared before Dhruva. He taught Dhruva various aspects of worshipping and penance. He taught Dhruva the mantra 'Om namo bhagavate vasudevaya.

' Om--O my Lord; Namo--my respectful obeisances unto You; Bhagavate--unto the Personality of Godhead; Vasudevaya--unto Lord Krsna, the son of Vasudeva.

TRANSLATION
O my Lord, the all-pervading Personality of Godhead, I offer my respectful obeisances unto You.

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In accordance with Narada's instructions, Dhruva observed penance and earned the blessings of Lord Narayana. He achieved this feat, which had eluded even mighty yogis. Then Narada Made King Uttanapada to realize his Mistake

DvAdasAksa MahaMantra: The Mantra has 12 petals or syllables, 

OmnamobhagavatevAsudevAya.      DvAdasAksa = DvAdasa pattraka = (10+2)12 petals = OmnamobhagavatevAsudevAya = 12- syllable mantra.

om1-na2-mo3-bha4-ga5-va6-te7-vA8-su9-de10-vA11-ya12 = Om, glory to Bhagavan  Vasudeva, whose essence is divine wisdom, whose rupa (form) is incomprehensible and who manifests as Brahma, Vishnu, and Siva.