B.G 4.38

न हि ज्ञानेन सदृशं पवित्रमिह विद्यते। तत् स्वयं योगसंसिद्धः कालेनात्मनि विन्दति ॥३८॥

na hi jñānena sadr̥śaṁ pavitramiha vidyate। tat svayaṁ yogasaṁsiddhaḥ kālenātmani vindati ॥38॥

[न हि ज्ञानेन सदृशं पवित्रम् इह विद्यते। तत् स्वयं योग संसिद्धः कालेन आत्मनि विन्दति॥
na = not; hi = indeed; jñānena = by transcendental knowledge; sadr̥śaṁ = similar; pavitram = purifying, beneficial; iha = here; vidyate = come to light;। tat = that; svayaṁ = by itself; yoga = Yōga; saṁsiddhaḥ = benevolent perfection in; kālena = with time; ātmani = the supreme essence; vindati = attains;]

Indeed, there is nothing as purifying in this world as transcendental knowledge that comes to light. That transcendental knowledge is self sufficient to produce benevolent perfection of Yōga, and over time attains the supreme essence.

Gīta Bhāshya 4.38

Verses 3.36 to 38 praise the transcendental knowledge as the primary cause responsible for liberation.

करणभूतम् ज्ञानं स्तौति पुनः श्लोकत्रयेण ॥३८॥

karaṇabhūtam jñānaṁ stauti punaḥ ślokatrayeṇa ॥38॥

[karaṇabhūtam = the cause responsible; jñānaṁ = that transcendental knowledge; stauti = praises; punaḥ = again; ślokatrayeṇa = in the three verses (4.36-38);]

The three verses (from 4.36 to 38) praise the transcendental knowledge, which is the primary cause responsible for the attainment of liberation.