E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Loving or Grace Cup.
A large cup passed round from guest to guest at state banquets and city feasts. Miss Strickland says that Margaret Atheling, wife of Malcolm Kanmore, in order to induce the Scotch to remain for grace, devised the grace cup, which was filled with the choicest wine, and of which each guest was allowed to drink ad libitum after grace had been said. (Historic Sketches.)