Regarding Mu^awiah, we say as Imam Abul Hassan al-Ash^ari said:
قال إمام أهل السنة أبو الحسن الأشعري رضي الله عنه:
"إن مقاتلي علي ءاثمون لكنَّ ثلاثةً منهم مغفور لهم طلحة والزبير وعائشة رضي الله عنهم،
أما البقيّة فيجوز أن يغفر الله لهم على قاعدة أهل السنة في جواز الغفران للمذنب ما لم يكفر".
This means: "All those who fought Imam Aliy are sinful except for three that were forgiven: Talhah, az-Zubeir, and ^Aishah Radiallahu ^Anha. As for the rest it's possible that Allah would forgive them according to the rule of Ahlus-Sunnah that a sinful Muslim can be forgiven as long as he does not balspheme".
Similar statements are reported by Imam Abu Mansur al-Baghdadiy, al-Bayhaqiy reporting from ash-Shafi^iy that those who fought Imam ^Aliy (Radiallahu ^Anhu) are aggressors (bughat):
نَقَلَ الإمام الكبير عبد القاهر بن طاهر أبو منصور البغدادي الشافعي الأشعري إجماع أهل السنة على أن الصواب كان في صفين مع سيدنا عليّ رضي الله عنه وقال إن معاوية وأصحابه بَغَوا على سيدنا علي رضي الله عنه . اهـ .
وقد ذَكَرَ ذلك في كتابه الفَرق بين الفِرق في ءاخرِه عند ذكر ما أجمع عليه أهل السنة، وهذا الإمام أبو منصور قد قال فيه ابن حجر الفقيه : الأستاذ الكبير، إمام أصحابنا، وكذا أقرر في دروسي ما ذكره الحافظ البيهقي في كتاب الاعتقاد على مذهب السلف أهل السنة والجماعة حيث قال : وكلُّ من نازع أمير المؤمنين عليّ بن أبي طالب في إمارته فهو باغٍ على هذا عهدت مشايخنا وبه قال ابن ادريس يعني الشافعي رضي الله عنه . اهـ .
In that battle thousdans of Muslims were killed unjustly. Allah will be the judge for everyone, and He knows best. We should all unite under the Qur'an and Alsunna, teachings of the Prophet peace be upon him, which were passed on to use by the companions and Ahlul-Bayt (may Allah accept their good deeds).
The Sahabah (Prophet Muhammad's companions) loved dearly and respected Ahlul-Bayt (Family of the Prophet peace be upon him).
However some Shia claim that only Ahlulbayt are righteous, and that the companions are not. Some of them cuss and curse the companions, namely the first three Khulafa, Imams Abu Bakr, Omar and Othman (Radiallahu ^Anhum); claiming that the caliphate was taken from Imam Aliy by force! But history is clear on the fact that Imam Aliy himself gave elegance to these honorable Khulafas and that he was the fourth Khalifah. He respected them highly and they respected him highly for his vast knowledge and relation to the Prophet peace be upon him. There are many narrations of examples of this mutual love and respect:
1. Imam Abu Hurairah once was on a horse, he saw Imam al-Hussein walking, with dust on his shoes. Then Imam Abu Hurairah dismounted the horse and bent down and cleaned his shoe for him from dust, and he said: "This is how we treat Ahlul-bayt". So he loved them.
2. Imam ^Aliy Radiallahu ^Anhu had a daughter and he gave her in marriage to our Master Omar Radiallahu ^Anhum.
3. Imam ^Aliy had three children that he named: Abu Bakr, Omar and Othman.
4. Likewise Imam al-Hussein had three children with the same names: Abu Bakr, Omar, and Othma.
5. Also Imam al-Hassan had a son named Abu Bakr. This indicates their love and respect to the Sahabah companions of our Prophet (Sallallahu ^Alayhi Wa Sallam).
And we, as Ahlus-Sunnah Wal Jama^ah, hundreds of Millions of Muslims today, regard and love highly the great and noble grand son of our beloved Prophet Muhammad peace be upon him, the great martyr Imam al-Husein, the son of Aliyy may Allah raise their ranks and accept their good deeds.