Musannaf Ibn Abi Shayba 27:56

Al-Ala’ ibn ‘Asim narrated to us, from Hammad ibn Zayd, from Ayyub, from Abu Qilabah, from Abu Asma’, from Thawban, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah gathered the earth for me, so I saw its easts and its wests. And the dominion of my nation will surely reach what was gathered for me of it. And I was given the two treasures: the red and the white." Hammad said: And I heard him once say: "So I interpreted them as the dominion of Persia and Rome." "And I asked my Lord for my nation that He would not destroy them by a widespread famine, and that He would not empower an enemy against them from outside themselves who would violate their sanctuary. And my Lord said: 'O Muhammad, indeed when I decree a decree, it is not turned back. And I grant you for your nation that I will not destroy them by a widespread famine, and I will not empower an enemy against them from outside themselves who would violate their sanctuary, even if those from all its regions—or he said: from its regions—gathered against them.'"