Togidres han thise thre hir trouthes plight
To lyve and dyen ech of hem for oother,
As though he were his owene ybore brother.
– Geoffrey Chaucer
The Canterbury Tales, The Pardoner’s Tale. The three rioters pledge an oath to live and die each for the other. There is a tragic irony in this, because at the end of the tale they do die for each other. Abandoning their pledge of brotherhood, they murder one another. Thus they have committed the sin of swearing a false oath.