I still wish to write a number of extensive articles about The Superiority of Shree Ashtakshara Mantra in Kali-Yuga, because reading Puranas and Vaishnava-Tantras I always encounter sub-Chapters dedicated to The Superiority of Shree Narayana-Mantra.
Anyway, while my articles are baking out, here is a grand Praman from "Shree Varaha-Purana" and in the next post I will publish the entire Chapter to which this Praman belongs.
"SHREE VARAHA-PURANA", 49.31-32:
"The merit acquired by the worship for one year in Krita-Yuga, is acquired by the same for half a year in Treta-Yuga, by quarter of a year in Dvapara-Yuga and by the mere utterance of the Name "NARAYANA" in Kali-Yuga".