Musnad Ahmad 32:2069

'Affan narrated to us, Ibrahim Abu Isma'il al-Qannad narrated to us, Qatadah narrated to us, from Anas ibn Malik, from the Messenger of Allah, may Allah bless him and grant him peace, narrating from his Lord, the Almighty and Majestic, who said: "Your Lord says: When My servant approaches Me by a span, I approach him by a cubit; and when he approaches Me by a cubit, I approach him by an arm's span; and when he approaches Me walking, I approach him running."