Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.112.

Ahmad records that Abu Sa’id reported that the Prophet, peace be upon him, said, “Any Muslim who makes a supplication containing nothing that is sinful and nothing that involves breaking ties of blood relationships, will be given for it by Allah one of these three things: He may accept his request, or assign its reward for him in the next world, or turn away from him an equivalent amount of evil.” Those who heard it said, “We would, then, make many supplications.” The Prophet, peace be upon him, replied, “Allah is more than ready to answer what you ask.”