Kena Upanishad by Shankara Ācārya parts IV 7-9. The disciple asked: O Master, teach me the Upanishad. (The teacher replied:) The Upanishad has been taught thee. We have certainly taught thee the Upanishad about Brahman. The Upaniṣad that I have told you consists of nothing but what has already been presented as the Upaniṣad of the supreme Self. We say that this is the intention

Aitareya Upanishad by Shankara Ācārya parts I i 1-4. In the beginning [all] this verily was Ātman only, one and without a second. There was nothing else that winked. He bethought Himself: “Let Me now create the worlds.” He created these worlds: Ambhah (the world of water-bearing clouds), Marīci (the world of the solar rays), Mara (world of mortals), and Āp (the world of waters).

Aitareya Upanishad by Shankara Ācārya parts I ii 1-5. These Deities, thus created, fell into this great ocean. He (the Creator) subjected that Person (i.e. Virāṭa in the form of a lump) to hunger and thirst. They (the deities) said to Him (the Creator): “Find out for us an abode wherein being established we may eat food.” The Creator) brought them a cow.

Aitareya Upanishad by Shankara Ācārya parts I iii 1-14. He (the Creator) bethought Himself: “Here now are the worlds and the world-guardians. Let Me create food for them.” Thus is seen in the world the lordly persons can favour their own people. Therefore the supreme Lord, too, has independence in the matter of favouring or disfavouring all, since He is the Lord of all.

Aitareya Upanishad by Shankara Ācārya parts II 1 Introduction. The Reality, that is the creator, preserver, and destroyer of the universe, and is transcendental, omniscient, omnipotent, and all-knowing, created in due order, this entire universe beginning with space, without the help of any substance other than Himself. Then He entered by Himself into all living creatures for the sake of self-realisation. I am this Brahman.

Aitareya Upanishad by Shankara Ācārya parts II i 1-6. This [person] is, at first, the germ in a man. That which is the semen is here called the germ. This semen is the vigour (tejas) drawn from all limbs. The man bears the self (the semen) in the self (the body). When he pours the semen into a woman, he gives it a birth.

Aitareya Upanishad by Shankara Ācārya parts III i 1-4. There are Brāhmaṇas of modern times who crave for emancipation, hanker after the knowledge of Brahman, and realise that the achievement of identity with the Self of all follows from its (own) means, viz. the knowledge of Brahman, as revealed by the Vedas and well known in the councils of the knowers of Brahman.