Instructions to Ibn Abbas before talks with the Kharijites
Nahj al-Balāgha|Volume 1|Book 2|Chapter 77
لَا تُخَاصِمْهُمْ بِالْقُرْآنِ، فَإِنَّ الْقُرْآنَ حَمَّالٌ ذُو وُجُوهٍ، تَقُولُ وَيَقُولُونَ، وَلكِنْ حَاجِجْهُمْ بالسُّنَّةِ، فَإِنَّهُمْ لَنْ يَجِدُوا عَنْهَا مَحِيصاً.
Do not argue with them by the Qur’ān because the Qur’ān has many faces. You would say your own and they would say their own; but argue with them by the sunnah, because they cannot find escape from it.