Upanishads

A wise man should control speech by mind, mind by intellect, intellect by the great Atman, and that by the Peaceful One (the Paramatman or Supreme Self).

— Katha-Upanishad Part Third XIII, tr. Swami Paramananda · Upanishad Daily

These cows have drunk water, eaten grass and given milk for the last time, and their senses have lost all vigour. He who gives these undoubtedly goes to joyless realms.

— Katha-Upanishad Part First III, tr. Swami Paramananda · Upanishad Daily

His form is not to be seen. No one can see Him with the eye. He is perceived by the heart, by the intellect and by the mind. They who know this become immortal.

— Katha-Upanishad Part Sixth IX, tr. Swami Paramananda · Upanishad Daily

This is the best Support, This is the highest Support; he who knows this Support is glorified in the world of Brahman.

— Katha-Upanishad Part Second XVII, tr. Swami Paramananda · Upanishad Daily

He who knows this (wisdom of the Upanishad), having been cleansed of all sin, becomes established in the blissful, eternal and highest abode of Brahman, in the highest abode of Brahman.

— Kena-Upanishad Part fourth IX, tr. Swami Paramananda · Upanishad Daily