The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
47. And the Smritis state (that).
Vyâsa and others state in their smritis the highest Self is not afflicted by the pain of the individual soul, 'That highest Self is said to be eternal, devoid of qualities, nor is it stained by the fruits of actions any more than a lotus leaf by water. But that other Self whose essence is action is connected with bondage and release; again and again it is joined with the seventeenfold aggregate 1.'--On the ground of the particle 'and' (in the Sûtra) we have to supply 'and scripture also records that.' So, for instance, 'One of them eats the sweet fruit, the other looks on without eating' (Mu. Up. III, 1, i), and 'The one Self within all things is never contaminated by the misery of the world, being himself without' (Ka. Up. II, 5, ii).
Here the pûrvapakshin raises a new objection.--If there is only one internal Self of all beings, what room is there for permissions and prohibitions, worldly as well as Vedic? You must not reject this objection on the ground of your having proved that the individual soul is a part of the Lord, and that thus injunctions and prohibitions may, without any mutual interference, apply to the soul which is different from the Lord. For there are other scriptural passages which teach that the soul is not different from the Lord, and therefore not a part of him, as, for instance, the following ones:
Having sent forth that he entered into it' (Taitt. Up. 11, 6); There is no other seer but he' (Bri. Up. III, 7, 23); 'From death to death goes he who perceives therein any diversity' (Bri. Up. IV, 4, 19); 'Thou art that' (Kh. Up. VI, 8, 7); 'I am Brahman' (Bri. Up. I, 4, 10). Should you say that just from this concurrence of intimations of difference on the one hand and non-difference on the other hand it follows that the soul is a part of the Lord, we reply that such might be the case if the intention of the texts were to teach difference as well as non-difference. But the fact is that the texts aim solely at teaching non-difference, because through the knowledge of Brahman being the universal Self the highest end of man is obtained. About difference on the other hand mere occasional statements (anuvâda) are made as about something already established naturally (i.e. apart from scripture). Moreover, we have already maintained that Brahman as not composed of parts can have no parts. Hence it follows that the one highest Self which is within all beings appears as individual soul, and it therefore remains to show how injunctions and prohibitions are possible.
65:1 I.e. the subtle body consisting of the ten sense-organs, the five prânas, manas, and buddhi.