2 Samuel 10:1

And it came to pass after this, that the king of the children of Ammon died, and Hanun his son reigned in his stead.

The death of Nahash, king of the Ammonites, was followed by the reign of his son Hanun in his place. Nahash had shown kindness to David while David was a fugitive from the rage of Saul, and David desired to repay that favor with grateful appreciation by sending ambassadors bearing sympathy to Hanun upon his succession. That apparent kindness from Nahash had been prompted wholly by hostility to Saul as king of Israel, for the Ammonites hated the true God and stood as bitter enemies of Israel. The change of kings thus set the occasion both for a courteous and wholly unprovoked act by David and for the vast hostile coalition, sprung from jealousy of David's increasing power, that grew into the greatest wars and victories of his reign.