Śrīmad-Bhāgavatam · Text 10.6.44
Who is speaking and story frame
य एतत् पूतनामोक्षं कृष्णस्यार्भकमद्भुतम् ।
शृणुयाच्छ्रद्धया मर्त्यो गोविन्दे लभते रतिम् ॥ ४४ ॥
ya etat pūtanā-mokṣaṁ
kṛṣṇasyārbhakam adbhutam
śṛṇuyāc chraddhayā martyo
govinde labhate ratim
Any person who hears with faith and devotion about how Kṛṣṇa, the Supreme Personality of Godhead, killed Pūtanā, and who thus invests his hearing in such childhood pastimes of Kṛṣṇa, certainly attains attachment for Govinda, the supreme, original person.
Read Śrīla Prabhupāda's purport on Vedabase.io