This is a brief sub-gloss. For a fuller reading of this verse, see Madhusūdana, Śaṅkara, or Rāmānuja above.

Swiftly, quickly, he becomes one whose self is dharma, whose mind is set on dharma, and he ever, perpetually, attains peace, calm. Hear the supreme truth, O son of Kuntī: make a firm declaration, a settled vow, that My devotee, whose inmost self is offered to Me, does not perish. Further.

By the worship of Me, made by his love for Me and having no other purpose, having his sin shaken off, his rajas and tamas uprooted root and all, he swiftly becomes righteous of self; swiftly he becomes one whose mind is single on the worship of Me, free of obstacles and with all its accompaniments. Worship of this very form is what was indicated by the word 'duty' at the opening, in 'of this duty, scorcher of foes'. He goes to lasting peace: he goes to the everlasting, never-returning ceasing of the conduct that obstructs the attaining of Me. Kaunteya, do you yourself make the firm promise in this matter: one who has begun on the devotion to Me, even though mixed with conduct that obstructs, does not perish; rather, by the greatness of devotion to Me, having destroyed the whole brood of obstructions and reached the everlasting ceasing of obstruction, he swiftly becomes one of full devotion.

Why does he swiftly become righteous-souled? And this happens only among the gods, their portions and the like. So the Shandilya branch of the Samaveda says, 'not one who has not turned from evil conduct, not one without devotion, not one uncollected, but only one rightly devoted, of pure intent toward Vasudeva, becomes righteous; the divine seers and their portions become so, somewhere, through knowledge'. Hence, if anyone other than these becomes so, he is to be inferred to be a hypocrite. For those of ordinary sin, even a great devotion may somehow arise through the company of the good; for others there is ordinary devotion. As the Vishnu Purana says, 'he who comes to the thirst for wealth, of crooked mind and base conduct, know that there is no devotion in him' (Vishnu Purana 3.7.30), and 'that devotion, growing in one who has faith, makes a man dispassionate toward all else'. And the Moksha-dharma says, 'the Vedas have been well studied by me, O Lord of the worlds, my austerity is fulfilled, and no untruth have I spoken before; I ever do worship to my elders, and the secret of another I have never divulged; the four secret things I keep according to the scripture, and I am ever the same toward foe and friend; and I worship without ceasing that primal God, taken as refuge with one-pointed disposition; by these means, my being purified, how should I not see the endless Lord?' (Mahabharata 12.335.3-5). And because conduct is said to be a means to knowledge, and in the absence of knowledge there is no right devotion; for the Gautama supplementary hymns say, 'without knowledge, how devotion? and without devotion, how that knowledge?'; and the Bhagavata says, 'devotion, the experiencing of the supreme Lord, and dispassion toward all else, these three come at one time' (Bhagavata 11.2.42).