Authors:

The wicked are always ungrateful.

Miguel de Cervantes Saavedra, Quixote de la Mancha (don, fict.name.) (1847). “The history of don Quixote de la Mancha. From the Span. To which is prefixed a sketch of the life and writings of the author. Select libr. ed”, p.67
The wicked are always ungrateful.