The System of the Vedanta according to Badarayana's Brahma-Sutras and Cankara's Commentary c5.s3.t2.2

c5.s3.t2.2

But the same accommodation to national prejudices which determines the philosophers of the Vedânta to derive all their knowledge, even by the most tortuous procedure from the Veda, makes it also impossible for them to admit the Ṣûdra; for a condition precedent to the study of the Vedânta, is the study of the Veda and a knowledge of its contents (p. 316, 9), for this again, the Upanayanam (initiation by a teacher), to which the Ṣûdra cannot attain (p. 317, 2, 320, 6), as the law (smṛiti) further forbids the reading aloud of the Veda, even in the presence of a Ṣûdra (p. 322, 2. 6).