The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
32. Of those who have a certain office there is subsistence (of the body) as long as the office lasts.
The question here is whether for him who has reached true knowledge a new body originates after he has parted with the old one or not.--But an objection is here raised at the outset there is really no occasion for inquiring whether knowledge when reaching its perfection brings about its due effect, viz. complete isolation of the Self from all bodies or not; not any more than there is room for an inquiry whether there is cooked rice or not, after the process of cooking has reached its due termination; or, for an inquiry whether a man is satisfied by eating or not. Not so, we reply. There is indeed room for the inquiry proposed, as we know from itihâsa and purâna that some persons although knowing Brahman yet obtained new bodies. Tradition informs us, e.g. that Apântaratamas, an ancient rishi and teacher of the Vedas, was, by the order of Vishnu, born on this earth as Krishna Dvaipâyana at the time when the Dvâparayuga was succeeded by the Kaliyuga. Similarly Vasishtha, the son of Brahman's mind, having parted from his former body in consequence of the curse of Nimi, was, on the order of Brahman, again procreated by Mitra and Varuna. Smriti further relates that Bhrigu and other sons of Brahman's mind were again born at the sacrifice of Varuna. Sanatkumâra also, who likewise was a son of Brahman's mind, was, in consequence of a boon being granted to Rudra, born again as Skanda. And there are similar tales about Daksha, Nârada, and others having, for various reasons, assumed new bodies. Stories of the same kind are met with in the mantras and arthavâdas of Sruti. Of some of the persons mentioned it is said that they assumed a new body after the old body had perished; of others that they assumed, through their
supernatural powers, various new bodies, while the old body remained intact all the while. And all of them are known to have completely mastered the contents of the Vedas.
On the ground of all this the pûrvapakshin maintains that the knowledge of Brahman may, indifferently, either be or not be the cause of final release.
This we deny, for the reason that the continuance of the bodily existence of Aparantamas and others--who are entrusted with offices conducive to the subsistence of the worlds, such as the promulgation of the Vedas and the like--depends on those their offices. As Savitar (the sun), who after having for thousands of yugas performed the office of watching over these worlds, at the end of that period enjoys the condition of release in which he neither rises nor sets, according to Kh. Up. III, 11, 1, 'When from thence he has risen upwards, he neither rises nor sets. He is alone, standing in the centre;' and as the present knowers of Brahman reach the state of isolation after the enjoyment of those results of action, which have begun to operate, has come to an end, according to Kh. Up. VI, 14, 2, 'For him there is only delay so long as he is not delivered from the body;' so Aparântamas and other Lords to whom the highest Lord has entrusted certain offices, last--although they possess complete knowledge, the cause of release--as long as their office lasts, their works not yet being exhausted, and obtain release only when their office comes to an end. For gradually exhausting the aggregate of works the consequences of which have once begun, so as to enable them to discharge their offices; passing according to their free will from one body into another, as if from one house into another, in order to accomplish the duties of their offices; preserving all the time the memory of their identity; they create for themselves through their power over the material of the body and the sense organs new bodies, and occupy them either all at once or in succession. Nor can it be said that when passing into new bodies they remember only the fact of their former existence (not their individuality); for it is known that they preserve the sense
of their individuality 1. Smriti tells us, e.g. that Sulabhâ, a woman conversant with Brahman, wishing to dispute with Ganaka, left her own body, entered into that of Ganaka, carried on a discussion with him, and again returned into her own body. If in addition to the works the consequences of which are already in operation, other works manifested themselves, constituting the cause of further embodiments, the result would be that in the same way further works also, whose potentiality would in that case not be destroyed, would take place, and then it might be suspected that the knowledge of Brahman may, indifferently, either be or not be the cause of final release. But such a suspicion is inadmissible since it is known from Sruti and Smriti that knowledge completely destroys the potentiality of action. For Sruti says, 'The fetter of the heart is broken, all doubts are solved, all his works perish when He has been beheld who is high and low' (Mu. Up. II, 2, 8); and, 'When the memory remains firm, then all the ties are loosened' (Kh. Up. VII, 26, 2). And Smriti similarly says, 'As a fire well kindled, O Arguna, reduces fuel to ashes, so the fire of knowledge reduces all actions to ashes;' and, 'As seeds burned by fire do not sprout again, so the Self is not again touched by the afflictions which knowledge has burned.' Nor is it possible that when the afflictions such as ignorance and the like are burned, the aggregate of works which is the seed of affliction should be partly burned, but partly keep the power of again springing up; not any more than the seed of the Sâli, when burned, preserves the power of sprouting again with some part. The aggregate of works, however, whose fruits have once begun to develop themselves comes to rest through effecting a delay which terminates with the death of the body, just as an arrow discharged stops in the end owing to the gradual cessation of its impetus; this in agreement with Kh. Up. VI, 14, 2, 'For him there is only delay,' &c. We have thus shown that persons to whom an office is
entrusted last as long as their office lasts, and that nevertheless there is absolutely only one result of true knowledge.--In accordance with this, scripture declares that the result of knowledge on the part of all beings is equally final release, cp. 'So whatever Deva was awakened he indeed became that, and the same with Rishis and men' (Bri. Up. I, 4, 10). Moreover 1 it may be the case that (some) great rishis had attached their minds to other cognitions whose result is lordly power and the like, and that later on only when they became aware of the transitory nature of those results they turned from them and fixed their minds on the highest Self, whereby they obtained final release. As Smriti says, 'When the mahâpralaya has arrived and the highest (i.e. Hiranyagarbha) himself comes to an end, then they all, with well-prepared minds, reach together with Brahman the highest place.'--Another reason precluding the suspicion that true knowledge may be destitute of its result is that that result is the object of immediate intuition. In the case of such results of action as the heavenly world and the like which are not present to intuitional knowledge, there may be a doubt; but not so in the case of the fruit of true knowledge, with regard to which scripture says. 'The Brahman which is present to intuition, not hidden' (Bri. Up. III, 4, 1), and which in the passage, 'That art thou,' is referred to as something already accomplished. This latter passage cannot be interpreted to mean, 'Thou wilt be that after thou hast died;' for another Vedic passage declares that the fruit of complete knowledge, viz. union with the universal Self, springs up at the moment when complete knowledge is attained, 'The Rishi Vâmadeva saw and understood it, singing, "I was Manu, I was the sun."
For all these reasons we maintain that those who possess true knowledge reach in all cases final release.
237:1 Utpadyamânânâm aparimushitasmaratveऽpi gâtismaratvam eva na vasishthâdinânatvam ity âsaṅkyâha na keti. Ân. Gi.