As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school. But there are five other Astika or orthodox schools of Hindu philosophy: Purva Mimamsa, Samkhya, Yoga, Vaisheshika, and Nyaya. My question is about the Nyaya and Vaisheshika schools. Udayana's Nyaya Kusumanjali is a 10th century Nyaya-Vaisheshika work which seeks to logically prove the existence of God. In this excerpt from the Nyaya Kusumanjali, Udayana tries to refutes the Purva Mimamsa belief that objects have Shaktis or inherent capacities to do things:
"[H]ow in images, etc., do such ceremonies become effectual as those for inviting to deity to take up residence therein, etc.? We hold therefore that we must admit such a thing as a capacity produced by the rite Pratishtha which can be destroyed by the touch of impure persons as the Chandala, etc., which renders an image a fit object of worship." ... The 'special causes' are the various kinds of merit in the person. The deities become conciliated in the ceremonies of consecration, and show it by coming to take up their residence, i.e. by the appropriation of the image and self-consciousness thereto; but by the touch of an impure person such appropriation and self-consciousness are rendered void.
For those who don't know, Prana Pratishtha is a ritual where you invoke the presence of a god into a statue. My question is, what scriptures say that the presence of a god in a statue is removed if it's touched by a Chandala?
Note that I don't want answers that comment on the nature of the caste system, untouchability, etc. I just want a specific answer on the Praha Pratishtha point.