The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness (Kitab Al-Dhikr)
Muslim :: Book 35 : Hadith 6473
Hammam b. Munabbih reported so many ahadith from Abu Huraira and one out of them is this that Allah's Messenger (may peace be upon him) said that Allah thus stated: When My servant draws close to me by the span of a palm, I draw close to him by the space of a cubit, and when he draws close to Me by the space of a cubit, I draw close to him by the space (covered) by two hands, and when he draws close to Me by the space (covered by) two hands, I go in hurry towards him.