Yazid bin Dubay'ah al-Absi (may Allah have mercy on him) says: On the day of the Camel, when the people had turned in flight, the caller of Sayyiduna Ammar — or of Sayyiduna Ali (may Allah be pleased with them both) — announced: Indeed, no wounded man is to be finished off, no mawla (client) is to be killed, and whoever lays down his weapons is safe. This was hard on us.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16748