Musannaf Ibn Abi Shayba 37:449

Ibn ‘Ulayyah narrated to us, from Ayyub, from Abu Hayyan, from Abu Zur’ah ibn ‘Amr, from Abu Hurayrah, that a man said: "O Messenger of Allah, when is the Hour?" He said: "The one questioned about it is no more knowledgeable than the questioner. But I will tell you of its signs: when the slave-woman gives birth to her mistress, that is one of its signs; and when the barefoot, naked ones become the heads of the people, that is one of its signs; and when the shepherds of sheep compete in the construction of buildings, that is one of its signs. [It is] among five [things] that no one knows except Allah: 'Indeed, Allah [alone] has knowledge of the Hour and sends down the rain and knows what is in the wombs, and no soul perceives what it will earn tomorrow, and no soul perceives in what land it will die. Indeed, Allah is Knowing and Acquainted.'"