TERMINATION OF AGREEMENT OF SALE FOR PROPERTY

My parents executed an Agreement of Sale with an individual for the sale of their flat on April 25, 2019. In the agreement it was written that the Deed of Conveyance should be registered within a month of the execution of the Agreement of Sale. It was also written that if the purchaser backs out from the transaction, then the OWNER/VENDOR can sale the property to a third party. Now my parents have decided not to sale the property due to some personal reasons and have communicated the same to the PURCHASER. My parents have also told the PURCHASER to take back the token amount of Rs. 50,000/- given during the execution of the Agreement of Sale. But the PURCHASER is now threatening to take legal Action against my parents and he is forcing my parents to sell our flat. the PURCHASER is also not willing to take back the token amount of Rs. 50,000/-. Can the PURCHASER take any legal action? What future course of action can we take in this matter?