What is the ruling on supplicating against someone, believing him to be an oppressor, when in reality he is not, and will Allah answer such a supplication?

If a person supplicates against another, believing that the latter has wronged him, while in reality he has not, then his supplication against him will not be answered, and it will not harm the other person. This is because Allah Almighty is the One who answers supplications, and He is All-Knowing of the true nature of affairs. He does not wrong anyone even by an atom's weight.