One verse

Srimad Bhagavatam 12.3.52

12.3.52

कृते यद्ध्यायतो विष्णुं त्रेतायां यजतो मखै: । द्वापरे परिचर्यायां कलौ तद्धरिकीर्तनात् ॥ ५२ ॥

kṛte yad dhyāyato viṣṇuṁ tretāyāṁ yajato makhaiḥ dvāpare paricaryāyāṁ kalau tad dhari-kīrtanāt

kṛte
in the Satya-yuga
yat
which
dhyāyataḥ
from meditation
viṣṇum
on Lord Viṣṇu
tretāyām
in the Tretā-yuga
yajataḥ
from worshiping
makhaiḥ
by performing sacrifices
dvāpare
in the age of Dvāpara
paricaryāyām
by worshiping the lotus feet of Kṛṣṇa
kalau
in the Age of Kali
tat
that same result (can be achieved)
hari-kīrtanāt
simply by chanting the Hare Kṛṣṇa mahā-mantra.

Whatever result was obtained in Satya-yuga by meditating on Viṣṇu, in Tretā-yuga by performing sacrifices, and in Dvāpara-yuga by serving the Lord’s lotus feet can be obtained in Kali-yuga simply by chanting the Hare Kṛṣṇa mahā-mantra.