Allopanishad

Allah Upanishad or Allopanishad is a book of dubious origin supposedly from Atharva Veda and believed to be written during Akbar's reign.

Swami Dayanand Saraswati's book Satyarth Prakash (The Light of Truth) makes it clear that:

# The "Allopanishad" is not part of the Upanishad canon. It does not even appear in the "Atharva Veda". The book could have been written during the Mughal era (possibly during Akbar's reign) [http://www.satyarthprakash.com/ENGLISH/english_sp.htm]