Sahih Muslim 2675 a
Abu Huraira reported Allah's Messenger (ﷺ) 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, better than his (remembrance), 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 if he walks towards Me, I rush towards him.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، وَزُهَيْرُ بْنُ حَرْبٍ، - وَاللَّفْظُ لِقُتَيْبَةَ - قَالاَ حَدَّثَنَا جَرِيرٌ،
 عَنِ الأَعْمَشِ، عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم
 ‏
"‏ يَقُولُ اللَّهُ عَزَّ وَجَلَّ أَنَا عِنْدَ ظَنِّ عَبْدِي بِي وَأَنَا مَعَهُ حِينَ يَذْكُرُنِي إِنْ ذَكَرَنِي فِي نَفْسِهِ
 ذَكَرْتُهُ فِي نَفْسِي وَإِنْ ذَكَرَنِي فِي مَلإٍ ذَكَرْتُهُ فِي مَلإٍ هُمْ خَيْرٌ مِنْهُمْ وَإِنْ تَقَرَّبَ مِنِّي شِبْرًا
 تَقَرَّبْتُ إِلَيْهِ ذِرَاعًا وَإِنْ تَقَرَّبَ إِلَىَّ ذِرَاعًا تَقَرَّبْتُ مِنْهُ بَاعًا وَإِنْ أَتَانِي يَمْشِي أَتَيْتُهُ هَرْوَلَةً
 ‏"‏ ‏.‏