There is a verse in the Qur’an regarding the Companions of the prophet (sws) that reads: “they are gentle amongst themselves but harsh towards the enemies”. But the history says that the Companions have been fighting amongst themselves i.e. Hazrat Ali (rta) and Hazrat Mu’awiya (rta). Since the Qur’an can never be wrong there must be a problem with the history.

2. Verse 48:29 illustrates two opposite attitudes in the companions of the Prophet (sws). The verse says that the same people (i.e. Companions (rta) who have such a harsh attitude towards kuffar, are kind and merciful among themselves. The intention of the verse is not to describe a never ending law about the Companions. The verse only intends to draw a line between the kuffar and believers by explaining how the general attitude of a believer towards members of these two groups are drastically different. The verse was revealed as part of the mission of the Messenger (sws) in doing itmam al-hujjah (completing the reasoning for the truth), where the believers were gradually separated and isolated from the kuffar and the judgment of the Almighty was about to come in the shape of the believers winning over the kuffar despite having less worldly resources. Even at the time of the Prophet (sws) there were instances were conflicts between the companions had occurred. After all, the companions were only human beings. The verse however, as described above, points to a more general fact. Also as a technical note please consider that Mu’awiah, accepting Islam after the conquest of Mecca, was not among the closed companions of the Prophet (sws) who have been regularly praised in some of the verses of the Qur’an like the one you referred to.