Musnad Ahmad 30:382

Yazid narrated to us, Muhammad informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurairah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "When Allah finished the creation, He wrote in His Book, and it is with Him above the Throne: 'Verily, My mercy has preceded My wrath.'"