Musnad Abu Ya'la al-Mawsili 3:330

Abu Khaythama narrated to us, Jarir narrated to us, from al-A’mash, from Salama ibn Kuhayl, from Salim ibn Abi al-Ja’d, from Abdullah ibn Saba’ who said: Ali ibn Abi Talib delivered a sermon to us and said: "By the One who split the seed and created the soul, this—meaning his beard—will surely be dyed by this—meaning the blood of his head." A man said: "By Allah, no one says that except that we will exterminate his offspring." He (Ali) said: "I adjure you by Allah, or I ask you by Allah, that no one kills me except my killer." A man said: "Will you not appoint a successor, O Commander of the Faithful?" He said: "No, but I will leave you to that to which the Messenger of Allah (peace and blessings of Allah be upon him) left you." They said: "What will you say to Allah when you meet Him?" He said: "I will say: O Allah, You left me among them for as long as You willed, then You took me to Yourself and left You among them; so if You will, You will rectify them, and if You will, You will corrupt them."