Srimad Bhagavatam Canto 10, Chapter 12, Text 33

SB 10.12.33

pinahi-bhogotthitam adbhutam mahaj
jyotih sva-dhamna jvalayad diso dasa
pratiksya khe ’vasthitam isa-nirgamam
vivesa tasmin misatam divaukasam
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
From the body of the gigantic python, a glaring effulgence came out, illuminating all directions, and stayed individually in the sky until Krsna came out from the corpse’s mouth. Then, as all the demigods looked on, this effulgence entered into Krsna’s body.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Apparently the serpent named Aghasura, because of having received association with Krsna, attained mukti by entering Krsna’s body. Entering the body of Krsna is called sayujya-mukti, but later verses prove that Aghasura, like Dantavakra and others, received sarupya-mukti. This has been broadly described by Srila Visvanatha Cakravarti Thakura with references from the Vaisnava-tosani of Srila Jiva Gosvami. Aghasura attained sarupya-mukti, being promoted to the Vaikuntha planets to live with the same four-armed bodily features as Visnu. The explanation of how this is so may be summarized as follows.
 
The effulgence came out from the python’s body and became purified, attaining spiritual suddha-sattva, freedom from material contamination, because Krsna had stayed within the serpent’s body, even after the serpent’s death. One may doubt that such a demon, full of mischievous activities, could attain the liberation of sarupya or sayujya, and one may be astonished about this. But Krsna is so kind that in order to drive away such doubts, He had the effulgence, the individual life of the python, wait for some time in its individuality, in the presence of all the demigods.
 
Krsna is the full effulgence, and every living being is part and parcel of that effulgence. As proved here, the effulgence in every living being is individual. For some time, the effulgence remained outside the demon’s body, individually, and did not mix with the whole effulgence, the brahmajyoti. The Brahman effulgence is not visible to material eyes, but to prove that every living being is individual, Krsna had this individual effulgence stay outside the demon’s body for some time, for everyone to see. Then Krsna proved that anyone killed by Him attains liberation, whether sayujya, sarupya, samipya or whatever.
 
But the liberation of those who are on the transcendental platform of love and affection is vimukti, special liberation. Thus the serpent first entered the body of Krsna personally and mixed with the Brahman effulgence. This merging is called sayujya-mukti. But from later verses we find that Aghasura attained sarupya-mukti. Text 38 explains that Aghasura attained a body exactly like that of Visnu, and the verse after that also clearly states that he attained a completely spiritual body like that of Narayana. Therefore in two or three places the Bhagavatam has confirmed that Aghasura attained sarupya-mukti. One may then argue, How is it that he mixed with the Brahman effulgence? The answer is that as Jaya and Vijaya, after three births, again attained sarupya-mukti and association with the Lord, Aghasura received a similar liberation.
Srimad Bhagavatam Canto 10, Chapter 12, Text 32
Srimad Bhagavatam Canto 10, Chapter 12, Text 34