ab-bhaksah katicin masan
aradhayan mantram imam
om namo narayanaya
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
For a few months the sons of Prajapati Daksa drank only water and ate only air. Thus undergoing great austerities, they recited this mantra: “Let us offer our respectful obeisances unto Narayana, the Supreme Personality of Godhead, who is always situated in His transcendental abode. Since He is the Supreme Person [paramahamsa], let us offer our respectful obeisances unto Him.”
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
From these verses it is apparent that the chanting of the maha-mantra or the Vedic mantras must be accompanied by severe austerities. In Kali-yuga, people cannot undergo severe austerities like those mentioned herein — drinking only water and eating only air for many months. One cannot imitate such a process. But at least one must undergo some austerity by giving up four unwanted principles, namely illicit sex, meat-eating, intoxication and gambling. Anyone can easily practice this tapasya, and then the chanting of the Hare Krsna mantra will be effective without delay. One should not give up the process of austerity. If possible, one should bathe in the waters of the Ganges or Yamuna, or in the absence of the Ganges and Yamuna one may bathe in the water of the sea. This is an item of austerity. Our Krsna consciousness movement has therefore established two very large centers, one in Vrndavana and another in Mayapur, Navadvipa. There one may bathe in the Ganges or Yamuna, chant the Hare Krsna mantra and thus become perfect and return home, back to Godhead.