Kaṭha Upaniṣad 217

217

ya eṣa supteṣu jāgarti kāmaṃ kāmaṃ puruṣo nirmimāṇaḥ /
tad eva śukraṃ tad brahma tad evāmṛtam ucyate /
tasmiṃl lokāḥ śritāḥ sarve tad u nātyeti kaścana // etad vai tat ///2,2.8 //

8. This Purusha who wakes when all sleep, creating what was desired is certainly ‘the pure,’ that is Brahman and that is said to be immortal. All worlds are fastened on that; none passes beyond that. This verily is that.