Ustad Bediüzzaman talking on Dispute and discord among the believers- 6 –

Sixth Aspect

Spiritual life and correctness of worship will suffer as a result of enmity and rancour, since the purity of intention that is the means of salvation will be damaged. For a biased person will desire superiority over his enemy in the good deeds that he performs and will be unable to act purely for the sake of God. He will also prefer, in his judgement and dealings, the one who takes his side; he will be unable to be just. Thus the purity of intention and the justice that are the bases of all good acts and deeds will be lost on account of enmity and hostility.
The Sixth Aspect is extremely complex, but we will cut it short here since this is not the place to enlarge on it.