One mantram on which I have thorough and absolute initiation is Sri Vishnu Sahasranamam..
I can call five persons as my Guru..
Some boys of our agraharam, below the age ten, would be chased by three old men all in their seventies, and forced to sit in the praakaaram after the Garuda Mandapam of our Sekharipuram Lakshminarayanaswamy temple at 6-30 in the evening after the first Deeparadhana and we would be asked to accompany the elders in chanting Sahasranamam..
One was a Swaminatha Mama, One my own maternal Grandfather and another equally respected thatha.. whose name I am not able to recollect now, but his pious and simple form lingers before my eyes.
Then there will the Perumal and His Madam and Garuda Azhvar also listening..
(the Divine Couple Lakminarayana, Garuda Azhwar and the three elderly thathas were my five gurus)
If there are two dozen boys loitering in the street running around two or three would be caught, asked to wash legs and face, wear Vibhoothi and sit with the elders..
Initially, it was a torture and I could not utter any name properly..
But within a few days, the beauty of the names with its rhythm and sacredness percolated gradually into my mind..
So it is almost for fifty three years that I am under the spell of Vishvam Vishnur Vashatakaaro...
Someone who did not understand Vishnusahasranamam and its beauty was asking me the other day while I was chanting.. "After Wishing someone, and shouting at someone, you start calling bhoothams.. Are you trying to do some black magic?"