Those Who Speak ill Of The Sahaabah...
All the Companions of the Prophet صلى الله عليه وسلم were `Adool (just) and Sudooq (truthful). We do not revile anyone of them, nor do we mention them except in goodness.
Whatever took place between `Alee and Mu`aawiyah, then we remain silent about this. They will get twice the reward for their correct judgments and decisions, and they will still be rewarded for their incorrect judgments. As the Prophet صلى الله عليه وسلم said: “If a judge gives a verdict according to the best of his knowledge and his verdict is correct (i.e. agrees with Allaah and His Apostle's verdict) he will receive a double reward, and if he gives a verdict according to the best of his knowledge and his verdict is wrong, (i.e. against that of Allaah and His Apostle) even then he will get a reward.” [Saheeh al-Bukhaaree]
Those who speak ill of the Sahaabah, speak ill about Allaah and His Messenger. For verily, Allaah and His Messenger صلى الله عليه وسلم were pleased with them; but these evildoers are not.
Haafidh `Abul Qaasim ibn `Asaakir has documented in Tareekh Dimashq that Imaam al-Nasaa’i was asked about Mu`aawiyah Ibn Abi Sufyaan رضي الله عنه. His reply was:
“Islaam is like a house with a door. The door of Islaam is the Sahaabah. Whoever speaks ill of the Sahaabah seeks but to harm Islaam, just like one who knocks a door to enter a house. As for Mu`aawiyah, whoever speaks ill of him seeks to find a way to speak ill of the Sahaabah.” [Tahdheeb al-Kamaal, vol. 1 p. 338-339]