Imam Khomeini explains the matter in his famous work of "an exposition on Forty Hadith" as following:
It is narrated from many companions of the Prophet (S) that once as the Prophet (S) came to them they were engaged in wrangling over a religious issue.
The Prophet (S) of Islam was greatly displeased and was indignant to this extent that they had never seen him before in such an anger.
The Prophet (S) told them it was because of this habit of wrangling that their precursors were destroyed, and he added that a true believer would never wrangle.
The Prophet (S) asked them to stop wrangling and told them that he would not act as an intercessor to any wrangler. Wrangling occupies the second place after idolatry among the things forbidden by God Almighty.
The Prophet (S) is reported to have also said that unless a believer refrains from wrangling and altercation he cannot know the truth, in spite of his position being correct.