The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
2. But there is (a scriptural statement of the origination of ether).
The conjunction 'but' indicates the adoption of another alternative.--The origin of ether may not be stated in the Khândogya; but it is stated in other scriptural passages. For the text of the Taittirîyakas, after having introduced Brahman as the general subject-matter,--in the words, 'The true, knowledge, without end is Brahman,'--goes on to say, 'From that Self sprang ether' (Taitt. Up. II, 1).--Hence there arises a conflict of scriptural passages, the creation sometimes being said to begin with fire, sometimes with ether.--But may we not appropriately assume the two scriptural passages to form one syntactical whole?--It would be well indeed if we could do so, but a unity of the kind desired cannot be admitted, because the creator who is mentioned only once--in the passage 'he sent forth fire'--cannot be connected with two things to be created, as if the construction were 'He sent forth fire, he sent forth ether.'--But--an objection may be raised--we see that sometimes an agent, although^ mentioned once only, is yet
connected with two objects; as when we say 'after having cooked broth he now cooks rice.' We therefore may combine the two scriptural sentences into one, 'Brahman having created ether created fire.'--Such a combination of sentences, we reply, is not admissible here, because the Khândogya intimates that fire was created first, while the Taittirîyaka assigns the same position to ether, and because it is impossible that both should have been created first.--The same remarks apply to a further contradiction involved in the other scriptural passage, 'From that Self sprang ether,' &c.; for there also the material cause and the fact of origination, being mentioned only once, cannot he connected with fire as well as ether, so as to effect a sentence of the following kind, 'from that there sprang ether, from that there sprang fire.' Moreover the Taittirîyaka states separately that 'fire (sprang) from air 1."--With regard to this conflict of statements somebody now maintains the following view.
5:1 While the Khând, says that fire sprang from the Self.