Pippalada was an ancient Indian Vedic sage who was known to have written which ancient Sanskrit text, embedded inside Atharva Veda?
Pippalada: Pippalada was an ancient Indian Vedic sage and philosopher in Hindu mythology. Pippalada:  He is known to have written the Prashna Upanishad, which is among the ten mukhya(main) upanishads. Prashna Upanishad: The Prashna Upanishad (Sanskrit: प्रश्न उपनिषद् , Praśna Upaniṣad ) is an ancient Sanskrit text, embedded inside Atharva Veda, ascribed to "Pippalada" sakha of Vedic scholars.
Prashna Upanishad