Musnad Ahmad 30:3104

Waki’ narrated to us, he said: Hammad bin Salamah narrated to us, from Muhammad bin Ziyad, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, in Friday there is an hour; no man coincides with it while supplicating to Allah for good, except that Allah answers him."