Musannaf Ibn Abi Shayba 37:565

'Abdah ibn Sulayman narrated to us, from 'Asim, from Abu Zurarah and Abu 'Abd Allah, they both said: We heard 'Ali saying: "By Allah, I did not participate, and I did not kill, and I did not order, and I was not pleased"—meaning the killing of 'Uthman.