Abu Sa‘īd al-Khudri (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "The devil said: 'By Your Might O Lord, I will continue to misguide Your slaves as long as their souls remain in their bodies.' The Lord said: 'By My Might and My Majesty, I will continue to forgive them as long as they seek forgiveness from Me.'"
"The devil said: 'By Your Might O Lord, I will continue to misguide Your slaves as long as their souls remain in their bodies.'" i.e. the devil swore by Allah's Might that he will continue to misguide people as long as they are alive. "The Lord said: 'By My Might and My Majesty, I will continue to forgive them as long as they seek forgiveness from Me'", i.e. the Lord, the Most High, said in response to the devil: By My might and majesty I will continue to forgive them as long as they seek forgiveness for their sins from Me.