The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
9. But the declarations (of scripture) are equal (on the other side).
In reply to the averment made in Sûtra 3, we point out that there are declarations of scripture, of equal weight, in favour of the view that knowledge is not complementary to action. For there are scriptural passages such as, 'Knowing this the rishis descended from Kavasha said: For what purpose should we study the Veda? for what purpose should we sacrifice? Knowing this indeed the Ancient ones did not offer the Agnihotra;' and 'When Brâhmanas know that Self and have risen above the desire for sons, wealth, and worlds, they wander about as mendicants' (Bri. Up. III, 5). Scripture moreover shows that
[paragraph continues] Yâgñavalkya and others who knew Brahman did not take their stand on works. 'Thus far goes immortality. Having said so Yâgñavalkya went away into the forest' (Bri. Up. IV, 5, 15). With reference to the indicatory sign (as to the dependence of knowledge to work) which is implied in the passage, 'Sirs, I am going to perform a sacrifice,' we remark that it belongs to a section which treats of Vaisvânara. Now, the text may declare that a vidyâ of Brahman as limited by adjuncts is accompanied by works; but all the same the vidyâ does not stand in a subordinate relation to works since 'leading subject-matter' and the other means of proof are absent.
We now reply to the averment made in Sûtra 4.