Charles Ellicott Commentary 2 Samuel 10:3

"But the princes of the children of Ammon said unto Hanun their lord, Thinkest thou that David doth honor thy father, in that he hath sent comforters unto thee? hath not David sent his servants unto thee to search the city, and to spy it out, and to overthrow it?" — 2 Samuel 10:3 (ASV)

To search the city. —The capital, and almost the only city of the Ammonites was Rabbah; it was strongly fortified, and a knowledge of its interior would be important to an enemy. The suspicions of the Ammonites may have been roused by David’s growing power, and especially by his conquest of the neighboring Moabites.