"Kathopanishad ends with this"
Chapter-2. Section-5. Mantram- 1 to 18. 1 This is that eternal Asvattha Tree with its root above and branches below. That root, indeed, is called the Bright; That is Brahman and That alone is the Immortal. In That all worlds are contained and none can pass beyond. This, verily, is That. 2 Whatever there is—the whole universe—vibrates because it has gone forth from Brahman, which exists as its Ground. That Brahman is a great terror, like a poised thunderbolt. Those who know It become immortal. 3 From terror of Brahman, fire burns; from terror of It, the sun shines; from terror of It, Indra and Vayu and Death, the fifth, run. 4 If a man is able to realise Brahman here, before the falling asunder of his body, then he is liberated; if not, he is embodied again in the created worlds. 5 As in a mirror, so in the buddhi; as in a dream, so in the World of the Fathers; as in water, so Brahm