Is a prayer involving sin answered if the supplicant is not wronged, and what is the ruling on fearing such a prayer?

A supplication for sin will not be answered, based on the Prophet's (peace be upon him) saying: "The supplication of any servant will continue to be answered as long as he does not supplicate for sin or the cutting off of ties of kinship." Among the conditions for a supplication to be answered are: that what is supplicated for is not a sin, that the supplicant does not grow weary of supplicating, that he knows that no one can fulfill his need except Allah, that he supplicates with sincere intention and presence of heart, and that he avoids consuming unlawful earnings. There is no blame upon a person for fearing the supplication of others against him, due to the possibility that an injustice he was unaware of might have occurred.