The last two lines of the "Dies irae", meaning, in Latin, "Good Lord Jesus, give them rest" (in reference to the dead).

These lines are familiar to anyone who has heard a requiem (such as Mozart's Requiem), and also to fans of Monty Python, who might remember the line of penitant monks in Monty Python and the Quest for the Holy Grail who were walking along striking themselves with boards and chanting these lines.