We see Narad muni instructing Dhruva Maharaja the mantra: "Oṁ namo bhagavate vāsudevāya."
SB4.8.54: Oṁ namo bhagavate vāsudevāya. This is the twelve-syllable mantra for worshiping Lord Krsna.
But we are supposed to use the Hare Krishna maha-mantra for chanting.
Shall we use only Hare Krishna maha-mantra for chanting,and not any other mantra ? why ?
Please help me in clarifying this doubt.