Albert Barnes Commentary 1 Chronicles 19:2

"And David said, I will show kindness unto Hanun the son of Nahash, because his father showed kindness to me. So David sent messengers to comfort him concerning his father. And David`s servants came into the land of the children of Ammon to Hanun, to comfort him." — 1 Chronicles 19:2 (ASV)

Hanun - A Philistine king of this name is mentioned in the Assyrian inscriptions as paying tribute to Tiglath-pileser and warring with Sargon.