Musnad Ahmad 26:596

Isma'il narrated to us, Ayyub narrated to us, from Humayd ibn Hilal, from Abu Qatadah, from Usayr ibn Jabir, who said: A red wind blew in Kufa, and a man came whose only habit was saying: "O Abdullah ibn Mas'ud, the Hour has come." He said: He was reclining, so he sat up and said: "The Hour will not be established until inheritance is not divided, and no one rejoices over spoils." He said: "An enemy will gather against the people of Islam, and the people of Islam will gather against them." And he gestured with his hand toward Ash-Sham. I said: "Do you mean the Romans?" He said: "Yes." He said: "At that battle, there will be a severe apostasy." He said: "The Muslims will designate a vanguard for death that will not return unless they are victorious. They will fight until night separates them, and both sides will withdraw, neither having been victorious, and the vanguard will be annihilated. Then the Muslims will designate a vanguard for death that will not return unless they are victorious. They will fight until night separates them, and both sides will withdraw, neither having been victorious, and the vanguard will be annihilated. Then the Muslims will designate a vanguard for death that will not return unless they are victorious. They will fight until they reach evening, and both sides will withdraw, neither having been victorious, and the vanguard will be annihilated." "Then, when the fourth day comes, the rest of the people of Islam will advance against them, and Allah, the Mighty and Majestic, will place defeat upon them. They will be slaughtered in a massacre—either he said: 'the like of which has not been seen,' or he said: 'we have not seen the like of it'—to the extent that a bird passing by their flanks will fall down dead before it passes them." He said: "Sons of the same father, who were a hundred, will count themselves, and they will not find remaining among them except for one man. So over what spoils would one rejoice? Or what inheritance would be divided?" He said: "While they are like that, they will hear of a calamity greater than that. He said: A crier will come to them: 'The Dajjal has appeared among your offspring.' So they will cast aside what is in their hands and proceed. They will send ten horsemen as a vanguard." The Messenger of Allah (ﷺ) said: "I surely know their names, the names of their fathers, and the colors of their horses. They are the best horsemen on the face of the earth on that day."