The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
22. (Scripture) also declares that.
Scripture moreover contains a distinct intimation that the attributes under discussion are to be held apart. We read, Kh. Up. I, 8, 5, 'The form of that person is the same as the form of the other person, the joints of the one are the joints of the other, the name of the one is the name of the other.'--But how does this passage convey the desired intimation?--By expressly transferring the attributes of the person within the sun to the person within the eye; for this express transfer shows that the text looks upon the attributes of the two as separated by the difference of abode and therefore not to be combined (unless specially enjoined to be so combined).--The conclusion therefore is that the two secret names are to be held apart.