The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
26. And there is need of all (works), on account of the scriptural statement of sacrifices and the like; as in the case of the horse.
We now consider whether knowledge has absolutely no need of the works enjoined on the different âsramas, or whether it has some need of them. Under the preceding Sutra we have arrived at the conclusion that as knowledge effects its own end the works enjoined on the âsramas are absolutely not required. With reference to this point the present Sutra now remarks that knowledge has regard
for all works enjoined on the âsramas, and that there is not absolute non-regard.--But do not the two Sûtras thus contradict each other?--By no means, we reply. Knowledge having once sprung up requires no help towards the accomplishment of its fruit, but it does stand in need of something else with a view to its own origination.--Why so?--On account of the scriptural statements of sacrifices and so on. For the passage, 'Him Brâhmanas seek to know by the study of the Veda, by sacrifice, by gifts, by penance, by fasting' (Bri. Up. IV, 4, 22), declares that sacrifices and so on are means of knowledge, and as the text connects them with the 'seeking to know,' we conclude that they are, more especially, means of the origination of knowledge. Similarly the passage, 'What people call sacrifice that is really brahmakarya' (Kh. Up. VIII, 5, i). by connecting sacrifices and so on with brahmakarya which is a means of knowledge, intimates that sacrifices &c. also are means of knowledge. Again the passage, 'That word which all the Vedas record, which all penances proclaim, desiring which men live as religious students, that word I tell thee briefly, it is Om' (Ka. Up. I, 2, 15), likewise intimates that the works enjoined on the âsramas are means of knowledge. Similarly Smriti says, 'Works are the washing away of uncleanliness, but knowledge is the highest way. When the impurity has been removed, then knowledge begins to act.'
The phrase, 'as in the case of the horse,' supplies an illustration on the ground of suitability. As the horse, owing to its specific suitability, is not employed for dragging ploughs but is harnessed to chariots; so the works enjoined on the âsramas are not required by knowledge for bringing about its results, but with a view to its own origination.