Musnad Abu Ya'la al-Mawsili 116:55

Ahmad narrated to us, Hajjaj ibn Muhammad narrated to us, he said: Shu'bah narrated to me, he said: I heard Qatadah ibn Di'amah narrating from Anas that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Your Lord says: If the servant draws near to Me by a span, I draw near to him by a cubit; and if he draws near to Me by a cubit, I draw near to him by an arm's span; and if he comes to Me walking, I come to him rushing."