Al-Baqarah, Ayat 152.
Abu Hurairah RA:
The Prophet SAW said, "Allah SWT says, I am just as My slaves thinks I am, (i.e. I am Able to do for him what he thinks I can do for him) and I am with him if he remembers Me in himself, I too, remember him in Myself; and if he remembers Me in a group of people, I remember him in a group that is better than them; and if he comes one span nearer to Me, I go one cubit nearer to him; and if he comes 1 cubit nearer to Me, I go a distance of two outstretched arms nearer to him; and if he comes to Me walking, I go to him running."
Sahih Al-Bukhari, Vol 9, Hadith No 502.