The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
13. In the case of (the text of) some (the Kânvas) where food is not mentioned, (the number five is made full) by the light (mentioned in the preceding mantra).
The Kânva-text, although not mentioning food, makes up the full number five, by the light mentioned in the mantra preceding that in which the five-people are spoken of. That mantra describes the nature of Brahman by saying, 'Him the gods worship as the light of lights.'--If it be asked how it is accounted for that the light mentioned in both texts equally is in one text to be employed for the explanation of the five-people, and not in the other text; we reply that the reason lies in the difference of the requirements. As the Mâdhyandinas meet in one and the same mantra with breath and four other entities enabling them to interpret the term, 'the five-people,' they are in no need of the light mentioned in another mantra. The Kânvas, on the other hand, cannot do without the light. The case is analogous to that of the Shodasin-cup, which, according to different
passages, is either to be offered or not to be offered at the atirâtra-sacrifice.
We have proved herewith that Scripture offers no basis for the doctrine of the pradhâna. That this doctrine cannot be proved either by Smriti or by ratiocination will be shown later on.