Bhagavadgita 2.55-72

The Blessed Lord said:
When a man completely casts away, O Pârtha, all the desires of the mind, satisfied in the Self alone by the Self, then is he said to be one of steady wisdom.

He whose mind is not shaken by adversity, who does not hanker after happiness, who has become free from affection, fear, and wrath, is indeed the Muni of steady wisdom.

He who is everywhere unattached, not pleased at receiving good, nor vexed at evil, his wisdom is fixed.

When also, like the tortoise its limbs, he can completely withdraw the senses from their objects, then his wisdom becomes steady.

Objects fall away from the abstinent man, leaving the longing behind. But his longing also ceases, who sees the Supreme.

The turbulent senses, O son of Kunti, do violently snatch away the mind of even a wise man, striving after perfection.

The steadfast, having controlled them all, sits focussed on Me as the Supreme. His wisdom is steady, whose senses are under control.

Thinking of objects, attachment to them is formed in a man. From attachment longing, and from longing anger grows.

From anger comes delusion, and from delusion loss of memory. From loss of memory comes the ruin of discrimination, and from the ruin of discrimination he perishes.

But the self-controlled man, moving among objects with senses under restraint, and free from attraction and aversion, attains to tranquillity.

In tranquillity, all sorrow is destroyed. For the intellect of him who is tranquil-minded, is soon established in firmness.

No knowledge (of the Self) has the unsteady. Nor has he meditation. To the unmeditative there is no peace. And how can one without peace have happiness?

For, the mind which follows in the wake of the wandering senses, carries away his discrimination, as a wind (carries away from its course) a boat on the waters.

Therefore, O mighty-armed, his knowledge is steady, whose senses are completely restrained from their objects.

That which is night to all beings, in that the self-controlled man wakes. That in which all beings wake, is night to the Self-seeing Muni.

As into the ocean,—brimful, and still,—flow the waters, even so the Muni into whom enter all desires, he, and not the desirer of desires, attains to peace.

That man who lives devoid of longing, abandoning all desires, without the sense of 'I' and 'mine,' he attains to peace.

This is to have one's being in Brahman, O son of Prithâ. None, attaining to this, becomes deluded. Being established therein, even at the end of life, a man attains to oneness with Brahman.
The end of second chapter, designated The Way of Knowledge.