Musnad Abu Ya'la al-Mawsili 154:130

Abu Khaythama narrated to us, Abdullah bin Yazid narrated to us, Sa'id bin Abi Ayyub narrated to us, he said: Abu Hani' narrated to me, from 'Abbas al-Hajari, from Abdullah bin 'Umar, that a man came to the Messenger of Allah (may Allah bless him and grant him peace) and said: "My servant does evil and acts unjustly, so should I beat him?" He said: "Pardon him every day seventy times."