Narayana–parayana means my life is now dedicated for Narayana. Narayana, Krsna, Visnu, they're the same. So that is qualification, if you simply take it as vow that "From this day my life is dedicated to Narayana, Krsna." Sarvopadhi vinirmuktam tat paratvena nirmalam [Cc. Madhya 19.170]. As soon as we take this vow, that "From this day my life is dedicated to Krsna. Krsna wants everyone to surrender. I surrender. I believe," from that day you become free from all designation. Simply this determination, that "From this day I belong to Narayana, or Krsna. Whatever He wants…"

From Srila Prabhupada's lecture on Srimad-Bhagavatam 6.1.17 — May 17, 1976, Honolulu