Supplication as decreasing hardships

Q: Can Du`a' (supplication) mitigate a calamity? Would Allah have mercy on us due to our Du`a'? If the answer is yes, why does Allah (Glorified and Exalted be He) afflict people with calamities although they make Du`a'?

A: Du`a' is an act of worship dedicated to Allah (Glorified and Exalted be He). Allah has ordered Muslims to supplicate to Him, saying, "Invoke Me, I will respond to your (invocation). Verily! Those who scorn My worship [i.e. do not invoke Me, and do not believe in My Oneness, (Islâmic Monotheism)] they will surely enter Hell in humiliation!" Allah (Exalted be He) also says, And when My slaves ask you (O Muhammad صلى الله عليه وسلم) concerning Me, then (answer them), I am indeed near (to them by My Knowledge). I respond to the invocations of the supplicant when he calls on Me (without any mediator or intercessor). So let them obey Me and believe in Me, so that they may be led aright. (Part No. 24; Page No. 244) Du`a' indeed mitigates or wards off calamities. It may even ward off what is greater than calamities. The Prophet (peace be upon him) said, Nothing can avert destiny except Du`a'. Calamities expiate for sins and raise the status of the afflicted Muslim, who should resort to patience and have confident anticipation of Allah's Recompense. The afflicted should not feel any dissatisfaction regarding the Divine Decree.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.