The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
22. The two others (i.e. the individual soul and the pradhâna) are not (the source of all beings) because there are stated distinctive attributes and difference.
The source of all beings is the highest Lord, not either of the two others, viz. the pradhâna and the individual soul, on account of the following reason also. In the first place, the text distinguishes the source of all beings from the embodied soul, as something of a different nature; compare the passage (II, i, 2), 'That heavenly person is without body, he is both without and within, not produced, without breath and without mind, pure.' The distinctive attributes mentioned here, such as being of a heavenly nature, and so on, can in no way belong to the individual soul,
which erroneously considers itself to be limited by name and form as presented by Nescience, and erroneously imputes their attributes to itself. Therefore the passage manifestly refers to the Person which is the subject of all the Upanishads.--In the second place, the source of all beings which forms the general topic is represented in the text as something different from the pradhâna, viz. in the passage, 'Higher than the high Imperishable.' Here the term 'Imperishable' means that undeveloped entity which represents the seminal potentiality of names and forms, contains the fine parts of the material elements, abides in the Lord, forms his limiting adjunct, and being itself no effect is high in comparison to all effects; the whole phrase, 'Higher than the high Imperishable,' which expresses a difference then clearly shows that the highest Self is meant here.--We do not on that account assume an independent entity called pradhâna and say that the source of all beings is stated separately therefrom; but if a pradhâna is to be assumed at all (in agreement with the common opinion) and if being assumed it is assumed of such a nature as not to be opposed to the statements of Scripture, viz. as the subtle cause of all beings denoted by the terms 'the Undeveloped' and so on, we have no objection to such an assumption, and declare that, on account of the separate statement therefrom, i.e. from that pradhâna, 'the source of all beings' must mean the highest Lord.--A further argument in favour of the same conclusion is supplied by the next Sûtra.