Did Imam Ali (as) forgive Zubair in Battle of Jamal when he(Zubair) turned back when Imam Ali (as) reminded him the Hadith of Rasool (saww) during battle of Uhad that(Zubair you will draw your sword against Ali);and sentenced his murderer the Hell.
Imam Ali was saddened that Zubair was killed. However Zubair did not truly repent. He just left the battlefield. If he had repented he would have joined the side of Imam Ali.