Khalid narrates from Jubayr bin Nufayr (may Allah have mercy on him) that he said: Come, take us to a Companion of the Messenger of Allah (peace and blessings be upon him). He says: We came to him, and he (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "The Romans will make peace with you; then you will together fight an enemy and obtain spoils of war, return safe and sound, and halt at a place called Dhu Tulul. There a Christian man will raise the cross and say that the cross has prevailed. Then a Muslim will seize the cross and break it, because of which the Romans will become enraged and gather for battle."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18818