What is the ruling on congregational prayer behind an Imam who discriminates among people in his dealings or work?

Congregational prayer behind a man is valid if he meets the conditions for imamate (sane, Muslim, male). It is best for the one who leads the people in prayer to be the most proficient among them in recitation and the most knowledgeable. It is not permissible for an Imam to lead people in prayer if they dislike him, based on the hadith of Abu Umamah. However, if the Imam is not unjust, then the sin is upon those who dislike him without a legitimate religious reason. Prayer behind him is valid, and his actions do not affect the validity of the prayer. His sin is upon him if his distinguishing actions result in injustice. The obligation is to offer sincere advice and enjoin good.