In accordance with the meaning of the verse:
No bearer of burdens can bear the burden of another,(6:164)
which expresses pure justice, to nurture rancour and enmity towards a believer is like condemning all the innocent attributes found in him on account of one criminal attribute, and is hence an act of great injustice. If you go further and include in your enmity all the relatives of a believer on account of a single evil attribute of his, then, in accordance with the following verse in which the active participle is in the intensive form,
Verily man is much given to wrongdoing,(14:34)
you will have committed a still greater sin and transgression, against which truth, the Shari‘a and the wisdom of Islam combine to warn you. How then can you imagine yourself to be right, and say: “I am in the right”?
In the view of truth, the cause for enmity and all forms of evil is in itself evil and is dense like clay: it cannot infect or pass on to others. If someone learns from it and commits evil, that is another question.
Good qualities that arouse love are luminous like love; it is part of their function to be transmitted and produce effects. It is for this reason that the proverb has come into being, “The friend of a friend is a friend,” and also that it is said, “Many eyes are beloved on account of one eye.”
So O unjust man! If such be the view of truth, you will understand now, if you have the capacity for seeing the truth, how great an offence it is to cherish enmity for the likeable and innocent brothers and relatives of a man you dislike.
 ‘Ali b. Abi Talib, Nahj al-Balagha, 748-9.