The Debate of Ibn 'Abbas with the Khawarij

Question:
And other than the tashahhud, how was it in the incident of Ibn 'Abbas (may Allah be pleased with him) with Khalid, and these are the verses by which he argued against them.

Answer:
His debate is mentioned in the books of narration, the books of athar; it is mentioned. He went out to them when they gathered intending to fight 'Ali (may Allah be pleased with him). He went out to them, debated with them, and six thousand of them returned; six thousand of them returned, repenting to Allah (Mighty and Majestic), because they were convinced by the answers of 'Abdullah ibn 'Abbas (may Allah be pleased with him). He argued with them using the Book and the Sunnah until six thousand of them returned. As for those who persisted, 'Ali (may Allah be pleased with him) fought them at al-Nahrawan until he killed them and executed judgment upon them, and praise be to Allah.