The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
29. If it be said that (Brahman is) not (denoted) on account of the speaker denoting himself; (we reply that this objection is not valid) because there is in that (chapter) a multitude of references to the interior Self.
An objection is raised against the assertion that prâna denotes Brahman. The word prâna, it is said, does not denote the highest Brahman, because the speaker designates himself. The speaker, who is a certain powerful god called Indra, at first says, in order to reveal himself to Pratardana, 'Know me only,' and later on, 'I am prâna, the intelligent Self.' How, it is asked, can the prâna, which this latter passage, expressive of personality as it is, represents as the Self of the speaker, be Brahman to which, as we know from Scripture, the attribute of being a speaker cannot be ascribed; compare, for instance, Bri. Up. III, 8, 8, 'It is without speech, without mind.' Further on, also, the speaker, i.e. Indra, glorifies himself by enumerating a number of attributes, all of which depend on personal existence and can in no way belong to Brahman, 'I slew the three-headed son of Tvashtri; I delivered the Arunmukhas, the devotees, to the wolves,' and so on. Indra may be called prâna on account of his strength. Scripture says, 'Strength indeed is prâna,' and Indra is known as the god of strength; and of any deed of strength people say, 'It is Indra's work.' The personal Self of a deity may, moreover, be called an intelligent Self; for the gods, people say, possess unobstructed knowledge. It thus being a settled matter that some passages convey information about the personal Self
of some deity, the other passages also--as, for instance, the one about what is most beneficial for man--must be interpreted as well as they may with reference to the same deity. Hence prâna does not denote Brahman.
This objection we refute by the remark that in that chapter there are found a multitude of references to the interior Self. For the passage, 'As long as prâna dwells in this body so long surely there is life,' declares that that prâna only which is the intelligent interior Self--and not some particular outward deity--has power to bestow and to take back life. And where the text speaks of the eminence of the prânas as founded on the existence of the prâna, it shows that that prâna is meant which has reference to the Self and is the abode of the sense-organs. 1
Of the same tendency is the passage, 'Prâna, the intelligent Self, alone having laid hold of this body makes it rise up;' and the passage (which occurs in the passus, 'Let no man try to find out what speech is,' &c.), 'For as in a car the circumference of the wheel is set on the spokes and the spokes on the nave, thus are these objects set on the subjects (the senses) and the subjects on the prâna. And that prâna indeed is the Self of prâgña, blessed, imperishable, immortal.' So also the following passage which, referring to this interior Self, forming as it were the centre of the peripherical interaction of the objects and senses, sums up as follows, 'He is my Self, thus let it be known;' a summing up which is appropriate only if prâna is meant to denote not some outward existence, but the interior Self. And another scriptural passage declares 'this Self is Brahman, omniscient' 2 (Bri. Up. II, 5, 19). We therefore arrive at
the conclusion that, on account of the multitude of references to the interior Self, the chapter contains information regarding Brahman, not regarding the Self of some deity.--How then can the circumstance of the speaker (Indra) referring to himself be explained?
100:1 The text runs, 'astitve ka prânânâm nihsreyasam,' and Go. Ân. explains 'astitve prânasthitau prânânâm indriyânâm sthitir ity arthatah srutim âha.' He as well as Ân. Gi. quotes as the text of the scriptural passage referred to 'athâto nihsreyasâdânam ity âdi.' But if instead of 'astitve ka' we read 'asti tv eva,' we get the concluding clause of Kau. Up. III, 2, as given in Cowell's edition.
100:2 Whence we know that the interior Self referred to in the Kau. Up. is Brahman.