tvam tu rajan marisyeti
pasu-buddhim imam jahi
na jatah prag abhuto ’dya
deha-vat tvam na nanksyasi
O King, give up the animalistic mentality of thinking, “I am going to die.” Unlike the body, you have not taken birth. There was not a time in the past when you did not exist, and you are not about to be destroyed.
At the end of the First Canto (1.19.15) King Pariksit stated:
tam mopajatam pratiyantu vipra
ganga ca devi dhrta-cittam ise
dvijopasrstah kuhakas taksako va
dasatv alam gayata visnu-gathah
“O brahmanas, just accept me as a completely surrendered soul, and let mother Ganges, the representative of the Lord, also accept me in that way, for I have already taken the lotus feet of the Lord into my heart. Let the snake-bird — or whatever magical thing the brahmana created — bite me at once. I only desire that you all continue singing the deeds of Lord Visnu.”
Even before hearing Srimad-Bhagavatam, King Pariksit was a maha-bhagavata, a great and pure devotee of Lord Krsna. There was actually no animalistic fear of death within the King, but for our sake Sukadeva Gosvami is speaking very strongly to his disciple, just as Lord Krsna speaks strongly to Arjuna in Bhagavad-gita.