Musnad Ahmad 30:2489

Yahya narrated to us, from Sulayman al-Taymi, from Anas, from Abu Hurayrah, who said—Yahya said: And perhaps he mentioned the Prophet, may Allah bless him and grant him peace—he said: "The servant does not draw near to Me by a span, except that I draw near to him by a cubit. And he does not draw near to Me by a cubit, except that I draw near to him by an arm-span—or a fathom."