Sahih Bukhari
Oneness, Uniqueness of Allah (Tawheed)
Volume: 009 / Book Number: 093 / Hadith Number: 596
Narrated Abu Huraira:
Allah's Apostle said, "Allah said, 'I am to my slave as he thinks of Me, (i.e. I am able to do for him what he thinks I can do for him). (See Hadith No. 502)