Brhan-naradiya Purana,
harinama para ye ca
ghore kali-yuge narah
te eva krtakrtyasca
na kalir badhate hi tan
hare kesava govinda
vasudeva jaganmaya
itirayanti ye nityam
na hi tam badhate kalih
“In this dark age of Kali-yuga, sincere devotees of the Supreme Lord should leave aside all other means for liberation and take full shelter of the holy name. This is their real responsibility and duty. There is unlimited bliss in chanting the different names of Krishna: Hari, Kesava, Govinda, Vasudeva and Jaganmaya. For one who chants constantly with unflinching faith, he remains unaffected by the reverses of Kali-yuga, because his heart has become purified by chanting.”
Brhan-naradiya Purana,
hari-nama-para ye ca
hari-kirtana tat parah
hari-puja-para ye ca
te krtarthah kalau-yuge
“Those who engage in chanting the holy name of Lord Hari (japa), are addicted to congregational chanting (kirtana), and engage in the worship of Lord Hari, have accomplished their desires in the age of Kali.d”
Padma Purana, Uttara Khanda 42nd Chapter,
dhyayan krte yajan yajnais
tretayam dvapare ’rcayan
yad apnoti tad apnoti
kalau sankirtya kesavam
“Whatever is achieved in Satya-yuga by meditation, in Treta by offering ritual sacrifices and in Dvapara by temple worship is achieved in Kali-yuga by chanting the names of Lord Kesava congregationally.”