The Vedanta Sutras, commentary by Sankaracharya (SBE34), tr. by George Thibaut  at sacred-texts.com
25. (And) because that which is stated by Smriti (i.e. the shape of the highest Lord as described by Smriti) is an inference (i.e. an indicatory mark from which we infer the meaning of Sruti).
The highest Lord only is Vaisvânara, for that reason also that Smriti ascribes to the highest Lord only a shape consisting of the threefold world, the fire constituting his mouth, the heavenly world his head, &c. So, for instance, in the following passage, 'He whose mouth is fire, whose head the heavenly world, whose navel the ether, whose feet the earth, whose eye the sun, whose ears the regions, reverence to him the Self of the world.' The shape described here in Smriti allows us to infer a Sruti passage on which the Smriti rests, and thus constitutes an inference, i.e. a sign indicatory of the word 'Vaisvânara' denoting the highest Lord. For, although the quoted Smriti passage contains a glorification 1,
still even a glorification in the form in which it there appears is not possible, unless it has a Vedic passage to rest on.--Other Smriti passages also may be quoted in connexion with this Sûtra, so, for instance, the following one, 'He whose head the wise declare to be the heavenly world, whose navel the ether, whose eyes sun and moon, whose ears the regions, and whose feet the earth, he is the inscrutable leader of all beings.'
145:1 And as such might be said not to require a basis for its statements.