2 Samuel 10:1-8 NIV
In the course of time, the king of the Ammonites died, and his son Hanun succeeded him as king. David thought, “I will show kindness to Hanun son of Nahash, just as his father showed kindness to me.” So David sent a delegation to express his sympathy to Hanun concerning his father.
When David’s men came to the land of the Ammonites, the Ammonite commanders said to Hanun their lord, “Do you think David is honoring your father by sending envoys to you to express sympathy? Hasn’t David sent them to you only to explore the city and spy it out and overthrow it?” So Hanun seized David’s envoys, shaved off half of each man’s beard, cut off their garments at the buttocks, and sent them away.
When David was told about this, he sent messengers to meet the men, for they were greatly humiliated. The king said, “Stay at Jericho till your beards have grown, and then come back.”
When the Ammonites realized that they had become obnoxious to David, they hired twenty thousand Aramean foot soldiers from Beth Rehob and Zobah, as well as the king of Maakah with a thousand men, and also twelve thousand men from Tob.
On hearing this, David sent Joab out with the entire army of fighting men. The Ammonites came out and drew up in battle formation at the entrance of their city gate, while the Arameans of Zobah and Rehob and the men of Tob and Maakah were by themselves in the open country.
NIV: New International Version