Musannaf Ibn Abi Shayba 3:3181

Abu Mu'awiyah narrated to us, from al-A'mash, from Ibrahim, who said: Abdullah used to recite it: "Famdhu ila dhikr Allah" (Proceed to the remembrance of Allah). And he would say: "If I were to recite it as 'Fas'aw' (Hasten), I would have hastened until my garment fell off."