E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Cup of Vows (The).
It used to be customary at feasts to drink from cups of mead, and vow to perform some great deed worthy of the song of a skald. There were four cups: one to Odin, for victory; one to Frey, for a good year; one to Niörd, for peace; and one to Bragi, for celebration of the dead in poetry.