Seven things are concealed from the eyes of man: the day of death, the day of consolation, the depth of judgment, the source of his livelihood, what is in the heart of his neighbor, the restoration of the kingdom of the house of David, and the uprooting of the kingdom of the "liable one" (i.e., Rome).
Seven Things Are Concealed from the Eyes of Man the Day
Mekhilta Tractate Vayassa 6:13