The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
26. Hence (the soul enters into unity) with the infinite (i.e. the highest Self); for this scripture indicates.
Hence i.e. because the non-difference of all Selfs is essential and their difference due to Nescience only, the individual soul after having dispelled Nescience by true knowledge passes over into unity with the highest Self. For this is indicated by scripture, cp. e.g. Mu. Up. III, 2, 9, 'He who knows that highest Brahman becomes even Brahman;' Bri. Up. IV, 4, 6, 'Being Brahman he goes to Brahman.'