In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Some people refrain from debating even if they are right and they site this hadeeth as evidence: “I guarantee a house in Jannah for one who gives up arguing, even if he is in the right”. [Ref 1] So they abandon debate.
Response: The one who abandons debate in the religion might not be completely right in doing so, because this might obstruct the truth and lead to defeat. [NB: The Shaikh (rahimahullaah) stated on page 243 that many people argue based on falsehood and defeat a person who is upon truth, so we do not say that such a person gained the upper hand over the truth, rather he gained the upper hand over the person who is upon truth due to his inability to debate][Ref 2]
However, it may be that a person is in the right whilst arguing with another person about something that is not related to the religion, for example he says: “I saw such and such person in the market” and the other person says, “Rather I saw him in the Masjid”, and thus an argument occurs between them. This is the type of argument mentioned in the hadeeth (i.e. the one that should be abandoned by a person even if he is in the right). As for the one who abandons debate in the path of aiding the truth, then he is not completely right in doing so and this action of his is not sanctioned by the hadeeth. [End of paraphrased quote] [Sharh Hilyati Taalibal Ilm. page 245]
Finally, you can find a series of very beneficial lectures on the principles of debate by Ustaadh Abu Hakeem on this link: https://soundcloud.com/masjidassunnahaston/sets/principles-of-debates
[Ref 1: Reported by Imaam Abu Dawud (rahimahullaah). Hadeeth Number 4800. Declared Hasan By Imaam Albaani (rahimahullaah) in his checking of Abu Daawud].