Musannaf Ibn Abi Shayba 38:141

Yahya ibn Adam narrated to us, he said: Musa ibn Muhammad al-Ansari narrated to us, he said: Yahya ibn Habban narrated to me, from Jabalah ibn Suhaym and so-and-so ibn Nadlah, they both said: Ali sent [a message] to the Khawarij and said: "Do not fight them until they are called to what they were upon regarding the provision of sustenance, in security from Allah and His Messenger." But they refused and insulted us.