(the Irish dubh-linn, the “black pool”). The chief part
of the city stands on land reclaimed from the river Liffey or the sea.
True as the Deil is in Dublin city. (Burns: Death and Dr. Hornbook.)
Probably Burns refers to the Scandinavian name Divelin,
which suggested first Divel
and then Devil or Deil
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894