Rāmānujaon Brahma Sūtra 1.3.37
Viśiṣṭādvaita Vedānta
Sūtra
तदभावनिर्धारणे च प्रवृत्तेः
tadabhāvanirdhāraṇe ca pravṛtteḥ
Sūtra translation
And on account of the procedure, on the ascertainment of the non-being of that.
That a Sûdra is not qualified for knowledge of Brahman appears from that fact also that as soon as Gautama has convinced himself that Jâbâla, who wishes to become his pupil, is not a Sûdra, he proceeds to teach him the knowledge of Brahman.