In a banquet speech at Windsor Castle, Charles said there can be "few happier symbols of success" than watching a relationship passed between generations - a reference to Prince William and Sayyid Theyazin, who were joint patrons of an Omani expedition.
The King spoke proudly about William as he hosted Sultan Haitham bin Tarik al Said at the start of his state visit on Tuesday, a few hours after the publication of Harry's GQ magazine interview, where he stated he "wants it to work out" with his family - but claimed others "don't want to".
William and Harry remain estranged but a spokesperson for Harry insisted it was not a "swipe" at his brother, although it is likely to be interpreted as such by some royal commentators.
Harry also spoke about the health of his father, the King, who has cancer, when asked whether having a sick parent was triggering after the traumatic death of his mother: "Yes but, you know, he's getting better."
Oman is a key Middle East ally of the UK and the visit comes as the United States' war against Iran continues, with the vital shipping route of the Strait of Hormuz, close to the coast of Oman, a key pinch point.
Charles praised Oman's "noble efforts" in trying to keep the vital sea lane open, describing it as a "great service" to the international community.
William and Theyazin sat together among 160 guests, who included Camilla, the Princess of Wales, the Princess Royal, Prime Minister Andy Burnham and senior Cabinet members.
"Our connections matter deeply and, in this regard, I have been especially delighted to see our sons, the Prince of Wales and His Highness Sayyid Theyazin, become joint patrons of the Jewel of Arabia Expedition," The King told the Sultan.
The two royal heirs were the figureheads of the expedition, a 30-day journey on foot, by camel and by 4×4 staged last year through Oman, following the route of British explorer Bertram Thomas in 1928.
"Your Majesty, there can be few happier symbols of success than a living relationship being passed from one generation to the next," the King said.
Harry's interview was released minutes after the Sultan's three-day state visit began with a formal welcome by Charles, Camilla, William and Kate, a carriage ride through Windsor and a military display of pomp and pageantry, all months in the planning and likely to be overshadowed by the interview.
The King spoke in Arabic, quoting poetry in an ancient form of the language and modern Arabic to greet the Sultan with the words "Welcome to a visitor of whom one never tires".
He also delivered his thoughts on the future: "Your Majesty, neither of us can know precisely what challenges our successors will face. Despite our constant efforts, climate change will regrettably alter the lands and seas they inherit".
"Artificial intelligence holds both promise and peril – unless managed with great wisdom and foresight. Competition for resources will test the international order in ways we cannot yet foresee.
"But this much we do know: our successors will rely on trusted friends. They will need allies prepared to work together across difference; to defend peace and international law; to marry innovation with stewardship; and to think not merely about the next year, but about generations to come."
Guests at the banquet were offered an after-dinner drink inspired by the Omani ritual of Kahwa – traditionally shared as a gesture of hospitality - reimagined for the occasion.
Royal chefs adapted Kahwa, usually an aromatic spiced Arabic coffee, using British teas and Windsor honey, with diners served Earl Grey and date, an iced mint and rose, and a warm cardamom-spiced blend sweetened with honey.
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