Shanti Parva 334.26

That which is minute, which is inconceivable, unmanifest, immobile, durable dissociated from the senses and the objects of the senses, as well as the (five) elements,—that is called the in-dwelling Soul of all existent creatures. That is known by the name of Kshetrajna. Transcending the three qualities of Sattva, Rajas, and Tamas, that is regarded as Purusha in the scriptures.