Has not the time arrived for the Believers that their hearts in all humility should engage in the remembrance of Allah and of the Truth which has been revealed (to them),And that they should not become like those to whom was given Revelation aforetime, but long ages passed over them and their hearts grew hard? For many among them are rebellious transgressors.[Qur'an 57:16]

Abu Huraira reported Allah's Messenger (may peace be upon him) as saying that Allah, the Exalted and Glorious, thus stated: I am near to 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 assembly..[Muslim 35:6471 Partial]