The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
5. To the elements (the soul, with prâna, goes), on account of the subsequent scriptural clause.
The soul joined by the prâna takes up its abode within the subtle elements which accompany heat and form the seed of the (gross) body. This we conclude from the clause, 'Breath in heat.'--But this passage declares, not that the soul together with the prâna takes up its abode in heat, but only that the prâna takes up its abode!--No matter, we reply; since the preceding Sûtra intercalates the soul in the interval (between prâna and tegas). Of a man who first travels from--Srughna to Mathurâ and then from Mathurâ to Pâtaliputra, we may say shortly that he travels from--Srughna to Pâtaliputra. The passage under discussion therefore means that the soul together with the prâna abides in the elements associated with heat.--But how are you entitled to draw in the other elements also, while the text only speaks of heat?--To this question the next Sûtra replies.