Abu Hurairah, radiyallahu 'anhu, reported that the Messenger of Allah, sallallahu 'alayhi wasallam, said:
"Allah the Almighty has said: 'Whosoever acts with enmity towards a closer servant of Mine (wali), I will indeed declare war against him. Nothing endears My servant to Me than doing of what I have made obligatory upon him to do. And My servant continues to draw nearer to Me with supererogatory (nawafil) prayers so that I shall love him. When I love him, I shall be his hearing with which he shall hear, his sight with which he shall see, his hands with which he shall hold, and his feet with which he shall walk. And if he asks (something) of Me, I shall surely give it to him, and if he takes refuge in Me, I shall certainly grant him it.'"