Rattlin' Willie goes to the fair to sell his fiddle. Someone urges him, "O, Willie, come sell your fiddle... And buy a pint o wine!" He refuses; "The warl' would think I was mad." He plays in "guid company"; his wife(?) says "Ye're welcome hame to me."
Like most Burns pieces, this has a traditional stub -- there is an item in Gammer Gurton's Garland,
John, come sell thy fiddle
And buy thy wife a gown.
No, I'll not sell my fiddle
For ne'er a wife in town.
(Baring-Gould-MotherGoose #91, p. 86)
The Baring-Goulds mention a note by Sir Walter Scott that Willie was a real fiddler who was tried and executed for murder. - RBW