How to speak to Khawarij

This is taken from the book [1]

Words of the Commander of the Faithful, ̃Ali b. Abi Talib

In one particular event, the Commander of the Faithful Ali b. Abi Talib sent Ibne Abbas towards the Khawarij (a group of individuals who had in fact, left the faith of Islam due to their deviant beliefs) to debate with them, however offered him the following advice:

“(O’ Ibne ̃Abbas) In your debates and discussions with them (the Khawarij), never resort to replying to them with the Qur`an, since surely the Qur`an contains verses which have various probabilities and possibilities to them (in their meaning and understanding). You shall speak to them (with the Qur`an), and they shall reply to you (with the Qur`an) and thus, your discussion with them will be prolonged. Rather, debate them using the sunnah since surely in that there is the straightforward and unequivocal reply and they will find no way to misrepresent the truth.” [2]

According to Ayatullah Jafar Subhani

This very valuable sentence clearly tells us that there are some verses of the Qur`an which have various possibilities in their meaning and it is not possible to specify one meaning to a verse without first going through the introductory steps (of understanding the verse). By merely possessing knowledge of the rules of the ̃Arabic language, the section of ambiguities will never be removed. Thus, the only way the ambiguities are removed is through the fourteen ways mentioned in this work.[1]

This hadith also relates to us the fact that all of the verses of the Qur`an are not straightforward proofs (which can be picked up and used without discretion) and thus in determining the true meaning where there is multiple possibilities of a particular verse, we must refer to other ways and means.

Reference
[1] Subhani, A. Jafar (2006). Introduction to the Science of Tafseer of the Qur'an. United Kingdom: World Federation of KSIMC. p. 72. ISBN 978-1-8984-4977-5.
[2] Nahjul Balagha, Letter 77