How the Ammonites repaid David's sympathy

In the book of 2 Samuel, chapter 10, King David sent messengers to the Ammonites as their king had died.

When the messengers arrived with David's expression of sympathy, the Ammonites seized the messengers, shaved half of their beards, tore their clothing, and sent them back to Israel.  The messengers were ashamed of how they looked, and David sent word to them that they were to remain in Jericho until their beards had fully grown.

Then, King David turned on the Ammonites and marched his best troops into their lands.  The Ammonites discovered the plot and asked the Syrians for help.  They obliged.

In the end, with the will of God amongst them, Israel won the battle and defeated both the Ammonites and the Syrians.