Musannaf Ibn Abi Shayba 38:3

Ibn Idris narrated to us, from Husayn, from Maysarah Abu Jamilah, who said: The first day the Khawarij spoke was the day of the Camel. They said: "How is it lawful for us to shed their blood, while their offspring and their wealth are forbidden to us?" Ali said: "The families are upon my chest and throat (i.e., my responsibility), and for you, there is five hundred [dirhams] for each one of you, which I have allocated for you, that which suffices you instead of the families."