It is obligated on every Muslim to examine himself, for indeed a person might incline towards [another] person who is upon truth based on his desires; then even before the truth is clear to him, he wishes that such and such person should be the one aided with the proofs or something else, so, his soul inclines [towards that person] because he [i.e. that person] is such and such [personality].

Therefore, even if that person is upon the truth, it is not permissible for this type of inclination to be present. If this type of inclination is present, even with the person upon truth, it is considered to be a trait of pre-Islamic ignorance.   This is an affair that does not cross the minds of many people.  Therefore, it is obligated on a Muslim in relation to affairs wherein people differ, that he is attentive to the fact that Allaah knows, sees and hears everything, and his intention [goal or aim] should only be that he [wants] to know the truth whether it is with this or that person. And in relation to this, Imaam Ash-Shaafi’ee said: “When I enter into a discussion [or debate], I am not bothered whether the truth is with me or with the other person.” So, he is not bothered nor does he wish that the truth is with him, rather he wishes that it is either with the other person or with him. This is the lofty moral conduct and the upright religion. http://www.rabee.net/ar/articles.php?cat=8&id=172