Abu Huraira reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying that Allaah, the Exalted and Glorious, thus stated: I live in the thought of My servant as he thinks about Me, and I am with him as he remembers Me, And if he remembers Me in his heart, I also remember him in My Heart, and if he remembers Me in assembly I remember him in the assembly, better than he (does that), and if he draws near Me by the span of a palm I draw near him by the cubit, and if he draws near Me by the cubit I draw near him by the space (covered by) two hands. And it he walks towards Me, I rush towards him [Muslim 6498].

Narrated by Abu Hurayrah: Allah's Messenger (peace be upon him) said, "If people sit in an assembly in which they do not remember Allah or invoke a blessing on their Prophet, vengeance will descend upon them. If Allah wills He will punish them, but if He wills He will forgive them." (Tirmidhi, 2272)