Muṇḍaka Upaniṣad
सत्यमेव जयते। अमृतत्त्व मानशुः॥
Part of the Atharva Veda, this Upaniṣad consists of 3 sections or Muṇḍakas. The central message in the Muṇḍaka Upaniṣad is about Brahman and is beautifully brought out with an initial division of knowledge into Parā Vidyā and Aparā Vidyā. However, the means of conveying it and the chronology of the messaging are somewhat different.