Musnad Abu Ya'la al-Mawsili 42:427

And from Abu Sa'id al-Khudri, that the Messenger of Allah, peace and blessings of Allah be upon him, said: "Indeed, the Shaytan said: 'By Your might, O Lord, I will not cease to lead Your servants astray as long as their souls are in their bodies.' The Lord said: 'By My might and My majesty, I will not cease to forgive them as long as they seek My forgiveness.'"