What does 1 Chronicles 19:4 mean?

After this, Nahash the king of the children of Ammon died, and his son reigned in his place.

David said, “I will show kindness to Hanun the son of Nahash, because his father showed kindness to me.” So David sent messengers to comfort him concerning his father. David’s servants came into the land of the children of Ammon to Hanun, to comfort him.

But the princes of the children of Ammon said to Hanun, “Do you think that David honors your father, in that he has sent comforters to you? Haven’t his servants come to you to search, to overthrow, and to spy out the land?”

Then some people went and told David how the men were treated. He sent to meet them; for the men were greatly humiliated. The king said, “Stay at Jericho until your beards have grown, and then return.”

When the children of Ammon saw that they had made themselves odious to David, Hanun and the children of Ammon sent one thousand talents of silver to hire chariots and horsemen out of Mesopotamia, out of Aram-maacah, and out of Zobah.

So they hired for themselves thirty-two thousand chariots, and the king of Maacah with his people, who came and encamped near Medeba. The children of Ammon gathered themselves together from their cities, and came to battle.