The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
8. Hereby air (also) is explained.
The present Sûtra extends the reasoning concerning ether to the air of which the ether is the abode. The different views about air also are to be arranged in an analogous manner. The pûrvapakshin maintains that the air is not a product, because it is not mentioned in that chapter of the Khândogya which treats of the origination of things. The opposite opinion is, that the air is mentioned in the parallel chapter of the Taittirîyaka ('from the ether sprang the air'). The two scriptural passages being of a conflicting nature, the pûrvapakshin maintains that the passage which declares the air to have originated must be taken in a secondary sense; firstly on account of the impossibility (of the literal sense being adopted), as shown (in the adhikarana treating of the ether); secondly on account of that passage which denies that it ever sets, 'Vâyu (the air) is the deity that never sets' (Bri. Up. I, 5, 22); and thirdly on account of those passages which declare it to be immortal. The final opinion on the other hand is, that air is a product; in the first place because this conclusion is conformable to the general tendency of scripture; and, in the second place, because it is generally admitted that whatever
is divided is an effect. The denial of its ever setting refers to the lower knowledge (aparâ vidyâ 1) and is merely a relative one, Vâyu not setting in the same way as fire, &c. The statement as to the immortality, &c. of air has already received its reply (in the adhikarana treating of the ether). Here it maybe asked why, ether and air being equally mentioned and not mentioned in the chapters treating of the origin of the world, one adhikarana is not considered to suffice for both, and why instead of that there is made a formal extension of the former reasoning to the latter case, although there is no difference between the two cases. To this we reply that there is indeed some reason for the question; that, however, the formal extension is made for the purpose of removing any doubts which might possibly be engendered in the minds of slow-witted people by mere words 2. For as, in the Samvargavidyâ and other passages, the glory of Vâyu is referred to as an object of worship; and as scripture says that he never sets, &c., some men might think that he is eternal.
19:1 In which Brahman is spoken of as to be meditated upon under the form of Vâyu.
19:2 Sabdânurodhiny eva saṅkâ na vastvanurodhinîti. Ân. Gi.