Srimad-Bhagavatam: Canto 4 - Chapter 1 - Verse 79

Sanskrit:

गीतं मयेदं नरदेवनन्दना:परस्य पुंस: परमात्मन: स्तवम् ।जपन्त एकाग्रधियस्तपो महत्चरध्वमन्ते तत आप्स्यथेप्सितम् ॥ ७९ ॥

ITRANS:

gītaṁ mayedaṁ naradeva-nandanāḥparasya puṁsaḥ paramātmanaḥ stavamjapanta ekāgra-dhiyas tapo mahatcaradhvam ante tata āpsyathepsitam

Translation:

My dear sons of the King, the prayers I have recited to you are meant for pleasing the Supreme Personality of Godhead, the Supersoul. I advise you to recite these prayers, which are as effective as great austerities. In this way, when you are mature, your life will be successful, and you will certainly achieve all your desired objectives without fail.

Purport:

If we persistently engage in devotional service, certainly all our desires will be fulfilled in due course of time.