Śrīmad-Bhāgavatam · Text 12.3.52
Who is speaking and story frame
कृते यद्ध्यायतो विष्णुं त्रेतायां यजतो मखै: ।
द्वापरे परिचर्यायां कलौ तद्धरिकीर्तनात् ॥ ५२ ॥
kṛte yad dhyāyato viṣṇuṁ
tretāyāṁ yajato makhaiḥ
dvāpare paricaryāyāṁ
kalau tad dhari-kīrtanāt
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.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.