The Upaniṣads — the philosophical core of the Vedic tradition, revealing the nature of Brahman, the Ātman, knowledge, action and liberation. The ten principal Upaniṣads together with select minor Vaiṣṇava Upaniṣads.
Three lines for whose sake the whole book is known: Nārada asks how to be saved in the age of Kali, and Brahmā gives him sixteen names — the great mantra. No fasting, no rite, no renunciation: only the Name, and it is called the sole means.