SB 9.5.27

ity etat puṇyam ākhyānam
 ambarīṣasya bhūpate
saṅkīrtayann anudhyāyan
 bhakto bhagavato bhavet
Synonyms: 
iti — thus; etat — this; puṇyam ākhyānam — most pious activity in history; ambarīṣasya — of Mahārāja Ambarīṣa; bhūpate — O King (Mahārāja Parīkṣit); saṅkīrtayan — by chanting, repeating; anudhyāyan — or by meditating upon; bhaktaḥ — a devotee; bhagavataḥ — of the Supreme Personality of Godhead; bhavet — one can become.
Translation: 
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.
Purport: 

Śrīla Viśvanātha Cakravartī Ṭhākura herein gives a very good example. When one is very eager for more and more money, he is not satisfied even when he is a millionaire or a multimillionaire, but wants to earn more and more money by any means. The same mentality is present in a devotee. The devotee is never satisfied, thinking, “This is the limit of my devotional service.” The more he engages in the service of the Lord, the more service he wants to give. This is the position of a devotee. Mahārāja Ambarīṣa, in his family life, was certainly a pure devotee, complete in every respect, because his mind and all his senses were engaged in devotional service (sa vai manaḥ kṛṣṇa-padāravindayor vacāṁsi vaikuṇṭha-guṇānuvarṇane). Mahārāja Ambarīṣa was self-satisfied because all of his senses were engaged in devotional service (sarvopādhi-vinirmuktaṁ tat-paratvena nirmalam/ hṛṣīkeṇa hṛṣīkeśa-sevanaṁ bhaktir ucyate). Nonetheless, although Mahārāja Ambarīṣa had engaged all his senses in devotional service, he left his home and went to the forest to concentrate his mind fully at the lotus feet of Kṛṣṇa, exactly as a mercantile man, even though complete in wealth, tries to earn more and more. This mentality of getting more and more engaged in devotional service puts one in the most exalted position. Whereas on the karma platform the mercantile man who wants more and more money becomes increasingly bound and entangled, the devotee becomes increasingly liberated.