Instructions to Ibn Abbas before talks with the Kharijites
Nahj al-Balāgha|Volume 1|Book 2|Chapter 77
ومن وصية له (عليه السلام) لعبد الله بن العباس لما بعثه للاحتجاج على الخوارج
Given to ‘Abdullāh ibn al-‘Abbās, at the time of his being deputed to confront the Khārijītes.