If you at all desire to rise to the throne of the King, then you have to undergo severe austerities. First of all you must satisfy the Supreme Personality of Godhead, Nārāyaṇa, and then, when you are favored by Him because of such worship, you shall have to take your next birth from my womb.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तपसाऽऽराध्य पुरुषं तस्यैवानुग्रहेण मे । गर्भे त्वं साधयात्मानं यदीच्छसि नृपासनम्
tapasā''rādhya puruṣaṃ tasyaivānugraheṇa me | garbhe tvaṃ sādhayātmānaṃ yadīcchasi nṛpāsanam
SB 4.8.13