Śrīmad-Bhāgavatam Suta Goswami said: After hearing all that was narrated to him by the self-realized and equipoised Sukadeva, the son of Vyasadeva, Maharaja Parikshit humbly approached his lotus feet. Bowing his head down upon the sage’s feet, the King, who had lived his entire life under the protection of Lord Vishnu, folded his hands in supplication and spoke as follows. Maharaja Parikshit said: I have now achieved the purpose of my life, because a great and merciful soul like you has shown such kindness to me. You have personally spoken to me this narration of the Supreme Personality of Godhead, Hari, who is without beginning or end. I do not consider it at all amazing that great souls such as yourself, whose minds are always absorbed in the infallible Personality of Godhead, show mercy to the foolish conditioned souls, tormented as we are by the problems of material life. I have heard from you this Śrīmad-Bhāgavatam, which is the perfect summary of all the Puranas and which perfectly describes the
Supreme Lord, Uttamaḥśloka. My lord, I now have no fear of Takshaka or any other living being, or even of repeated deaths, because I have absorbed myself in that purely spiritual Absolute Truth, which you have revealed and which destroys all fear.
anujānīhi māṁ brahman
vācaṁ yacchāmy adhokṣaje
praveśya visṛjāmy asūn
O brahmana, please give me permission to resign my speech and the functions of all my senses unto Lord Adhokshaja. Allow me to absorb my mind, purified of lusty desires, within Him and to thus give up my life. You have revealed to me that which is most auspicious, the supreme personal feature of the Lord. I am now fixed in knowledge and self-realization, and my ignorance has been eradicated. By knowing about the Lord and realization of his sweetness and powers, my ignorance has been destroyed. How did this arise? The supreme form, abode or lotus feet of the Lord have been shown by you. Suta Goswami said: Thus requested, the saintly son of Srila Vyasadeva gave his permission to King Parikshit. Then, after being worshiped by the King and all the sages present, Sukadev departed from that place.
parīkṣid api rājarṣir
ātmany ātmānam ātmanā
samādhāya paraṁ dadhyāv
aspandāsur yathā taruḥ
prāk-kūle barhiṣy āsīno
Maharaja Parikshit then sat down on the bank of the Ganges, upon a seat made of darbha grass with the tips of its stalks facing east, and turned himself toward the north. Having attained the perfection of yoga, he experienced full self-realization and was free of material attachment and doubt. The saintly King settled his mind within his spiritual self by pure intelligence and proceeded to meditate upon the Supreme Absolute Truth. His life air ceased to move, and he became as stationary as a tree.
In Sārārtha-darśini verse 12.6.11&13, Srila Vishvanatha Chakravarti Thakur explains that since Maharaja Parikshit already attained the abode of the Lord, the attack of Takshaka was a useless action. And the burning of his body was like the last rites performed by his son.
— Śrīmad-Bhāgavatam (Bhāgavata Purāṇa) » Canto 12: The Age of Deterioration » Chapter 6: Mahārāja Parīkṣit Passes Away» Verses: 1-10. Translations by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada.