Musnad Ahmad 30:2657

Waki' narrated to us, he said: Ubaydullah ibn Abd al-Rahman ibn Mawhab narrated to us, from his paternal uncle, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no Muslim who directs his face toward Allah, the Almighty and Majestic, in a request, except that He gives it to him; either He hastens it for him, or He stores it up for him."