आगमे ब्राह्मे विश्वासटिप्पन्यः

And on account of (Gautama) proceeding (to initiate Jābāla) on the ascertainment of (his) not being that (i.e. a Śūdra).

The Śūdras are not qualified for that reason also that Gautama, having ascertained Jābāla not to be a Śūdra from his speaking the truth, proceeded to initiate and instruct him. ‘None who is not a Brāhmaṇa would thus speak out. Go and fetch fuel, friend, I shall initiate you. You have not swerved from the truth’ (Cḥ. Up. IV, 4, 5); which scriptural passage furnishes an inferential sign (of the Śūdras not being capable of initiation).