The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
17. (This scripture) also shows, and it is likewise stated in Smriti.
That Brahman is without any difference is proved by those scriptural passages also which expressly deny that it possesses any other characteristics; so, e.g. 'Next follows the teaching by No, no' (Bri. Up. II, 3, 6); 'It is different from the known, it is also above the unknown' (Ke. Up. I, 4); 'From whence all speech, with the mind, turns away unable to reach it' (Taitt. Up. II, 9). Of a similar purport is that scriptural passage which relates how Bâhva, being questioned about Brahman by Vashkalin, explained it to him by silence, 'He said to him, "Learn Brahman, O friend," and became silent. Then, on a second and third question, he replied, "I am teaching you indeed, but you do not understand. Silent is that Self."' The same teaching is conveyed by those Smriti-texts which deny of Brahman all other characteristics; so, e.g. 'I will proclaim that which is the object of knowledge, knowing which one reaches immortality; the highest Brahman without either beginning or end, which cannot be said either to be or not to be' (Bha. Gîtâ XIII, 12). Of a similar purport is another Smriti-passage, according to which the omniform Nârâyana instructed Nârada, 'The cause, O Nârada, of your seeing me endowed with the qualities of all beings is the Mâyâ emitted by me; do not cognize me as being such (in reality).'