The Prashnopanishad is an ancient Sanskrit text, embedded inside Atharva Veda, ascribed to Pippalada sakha of Vedic scholars. It is a Mukhya (primary) Upanishad, and is listed as number 4 in the Muktika canon of 108 Upanishads of Hinduism.
The Prashna Upanishad is a 1st-millennium BCE Hindu text. Above: a manuscript page in Sanskrit, Devanagari script.
The Atharvaveda or Atharva Veda or Atharvana Veda is the "knowledge storehouse of atharvāṇas, the procedures for everyday life". The text is the fourth Veda, and is a late addition to the Vedic scriptures of Hinduism.
Rishi Caraka (above), the author of Caraka Samhita credits Atharvaveda as an inspiration.