King Nābhi understood that his son, Ṛṣabhadeva, was very popular among the citizens and among government officers and ministers. Understanding the popularity of his son, Mahārāja Nābhi enthroned Him as the emperor of the world to give protection to the general populace in terms of the Vedic religious system. To do this, he entrusted Him into the hands of learned brāhmaṇas, who would guide Him in administrating the government. Then Mahārāja Nābhi and his wife, Merudevī, went to Badarikāśrama in the Himālaya Mountains, where the King engaged Himself very expertly in austerities and penances with great jubilation. In full samādhi he worshiped the Supreme Personality of Godhead, Nara-Nārāyaṇa, who is Kṛṣṇa in His plenary expansion. By doing so, in course of time Mahārāja Nābhi was elevated to the spiritual world known as Vaikuṇṭha.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
विदितानुरागमापौरप्रकृतिजनपदो राजा नाभिरात्मजं समयसेतुरक्षायामभिषिच्य ब्राह्मणेषूपनिधाय सह मेरुदेव्या विशालायां प्रसन्ननिपुणेन तपसा समाधियोगेन नरनारायणाख्यं भगवन्तं वासुदेवमुपासीनः कालेन तन्महिमानमवाप
viditānurāgamāpauraprakṛtijanapado rājā nābhirātmajaṃ samayaseturakṣāyāmabhiṣicya brāhmaṇeṣūpanidhāya saha merudevyā viśālāyāṃ prasannanipuṇena tapasā samādhiyogena naranārāyaṇākhyaṃ bhagavantaṃ vāsudevamupāsīnaḥ kālena tanmahimānamavāpa
SB 5.4.5