What is the ruling of Islamic law regarding a house seller who withdraws the power of attorney from the buyer after three years, out of greed for an increased house price? What is the ruling on the buyer resorting to drawing up a fictitious sales contract to reclaim his right, and what is the ruling on the the questioner's testimony on this contract?

The issue of an agent buying for himself is a matter of dispute. The preponderant opinion is that the sale is valid if the principal has given explicit or customary permission, and if the sale is for the market price or more. The validity of a contract does not depend on its documentation, but rather on offer and acceptance, and other pillars and conditions. Neither of the contracting parties is permitted to rescind the sale after they have separated. If one of the parties acts treacherously due to the lack of documentation, the other party is permitted to use stratagems to obtain their right, as is anyone who assists them.