Abu al-Ghadiyah (may Allah have mercy on him) narrates: "I saw Sayyiduna Ammar bin Yasir (may Allah be pleased with them both) mention Sayyiduna Uthman bin Affan (may Allah be pleased with him) (with disparagement), so I said (to myself): 'If I get the upper hand over him (I will not spare him).' Then, when the day of Siffin came, Ammar (may Allah be pleased with him) was armed; he would charge until he entered the ranks of the people and then come out. Then I looked and saw that the armour had slipped off his knee and shin, so I aimed my spear at him, struck his knee, and then killed him." (At this) Sayyiduna Amr bin al-As (may Allah be pleased with him) said: "I heard the Messenger of Allah (peace and blessings be upon him) saying: 'The one who kills him (Ammar) and the one who strips him of his belongings are both in the Fire.'"
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Hammad bin Salamah except Yazid bin Harun."
Hadith Referenceالمعجم الأوسط / باب النون / 9252
Hadith Takhrij«أخرجه الحاكم فى «المستدرك» برقم: 5710، وأحمد فى «مسنده» برقم: 18054، وابن حجر فى «المطالب العالية» برقم: 4415»