Musannaf Ibn Abi Shayba 36:535

Muhammad ibn Numayr narrated to us, from Sufyan, from al-Aswad ibn Qays, from Abdullah ibn al-Harith al-Khuza'i, who said: I heard Umar saying in his sermon: "I saw last night a rooster pecking me, and I saw people keeping it away from me. And I swear by Allah, if I remain, I will surely set the lowest of the Muhajirun in the stipend at two thousand each." He did not remain but three [days] until the slave of al-Mughira, Abu Lu'lu'a, killed him.