Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.112A.
Section : Avoiding hastiness for acceptance of supplication..
Abu Hurairah reported that the Prophet, peace be upon him, said, “Your supplication will be answered if you are not impatient, and if you do not say, ‘I supplicated but my supplication was not heard’.” (Malik)