Kaṭha Upaniṣad 128

128

atha tṛtīyā vallī /
ṛtaṃ pibantau sukṛtasya loke guhāṃ praviṣṭau parame parārdhe /
chāyātapau brahmavido vadanti pañcāgnayo ye ca triṇāciketāḥ ///1,3.1 //

1. The two, who enjoy the fruits of their good deeds, being lodged in the cavity of the seat of the supreme, the knowers of Brahman call shadow and light, as also those who maintain five fires and have thrice propitiated the Nachiketa fire.