The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
11. And on account of (its) not being an instrument the objection is not (valid); for thus (scripture) declares.
The objection urged, viz. that there would result another sense-object, is not valid; because the prâna is not an
instrument. For we do not assume that the prâna is, like the eye, an organ because it determines a special sense-object. Nor is it on that account devoid of an effect; since scripture declares that the chief vital air has a specific effect which cannot belong to the other prânas. For in the so-called colloquies of the prânas we read in the beginning, 'The prânas quarrelled together who was best;' after that we read, 'He by whose departure the body seems worse than worst, he is the best of you;' thereupon the text, after showing how, on the successive departure of speech and so on, the life of the body, although deprived of one particular function, went on as before, finally relates that as soon as the chief prâna was about to depart all other prânas became loosened and the body was about to perish; which shows that the body and all the senses subsist by means of the chief prâna. The same thing is declared by another passage, 'Then prâna as the best said to them: Be not deceived; I alone dividing myself fivefold support this body and keep it' (Pr. Up. II, 3). Another passage, viz. 'With prâna guarding the lower nest' (Bri. Up. IV, 3, 12), shows that the guarding of the body depends on prâna. Again, two other passages show that the nourishing of the body depends on prâna, 'From whatever limb prâna goes away that limb withers' (Bri. Up. I, 3, 19), and 'What we eat and drink with it supports the other vital breaths.' And another passage declares that the soul's departing and staying depend on prâna, 'What is it by whose departure I shall depart, and by whose staying I shall stay?--The created prâna' (Pr. Up. VI, 3; 4).