Your health. The story is that Vortigern was invited to dine at the house of Hengist, when Rowena, the host's daughter, brought a cup of wine which she presented to their royal guest, saying, “Was hæ'l, hlaford cyning ” (Your health, lord king). (See Wassail.)
William of Malmesbury says the custom took its rise from the death of young King Edward the Martyr, who was traitorously stabbed in the back while drinking a cup of wine presented to him by his mother Elfrida.
Nævia sex cyathis, septem Justina bibatur, Quinque Lycas, Lyde quatuor, Ida tribus.
Martial, i. 72.
Three cups to Amy, four to Kate be given, To Susan five, six Rachel, Bridget seven.
E. C. B.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894