Musnad Ahmad 30:3094

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Sulayman, who said: I heard Dhakwan narrating from Abu Hurayrah, from the Prophet, peace and blessings of Allah be upon him, who said: "Allah, the Almighty and Majestic, said: 'My servant is as he thinks of Me, and I am with him when he calls upon Me. If he remembers Me in himself, I remember him in Myself. If he remembers Me in a gathering, I remember him in a gathering better and purer than them. If he draws near to Me by a span, I draw near to him by a cubit. If he draws near to Me by a cubit, I draw near to him by an arm's length. And if he comes to Me walking, I come to him at a run.'"