Śrīmad-Bhāgavatam · Text 9.5.27
Who is speaking and story frame
इत्येतत् पुण्यमाख्यानमम्बरीषस्य भूपते ।
सङ्कीर्तयन्ननुध्यायन् भक्तो भगवतो भवेत् ॥ २७ ॥
ity etat puṇyam ākhyānam
ambarīṣasya bhūpate
saṅkīrtayann anudhyāyan
bhakto bhagavato bhavet
Anyone who chants this narration or even thinks of this narration about the activities of Mahārāja Ambarīṣa certainly becomes a pure devotee of the Lord.
Read Śrīla Prabhupāda's purport on Vedabase.io