Consiðer this logic for instance: mr A and mr B were mutual friends. Mr A and mr B are friend of mr C. Mr A and mr B had a strong disagreement. Mr A and mr B departed. Mr C is still friends of mr A and mr B.
For mr C to be a just person if he cannot settle the fight between mr A and mr B then he must not be partial in his dealings with both parties. If mr C considers mr A in one area today then he must consider mr B in another area next time.
We should also be like mr C today: let's give others a chance as we go out to vote; a trial will convince you.