Hadad could have lived out his life in Egypt, but when news reached him in Egypt that King David was dead, he requested permission from Pharaoh to take his family and return to Edom. Pharaoh attempted to convince him to stay where he was, but Hadad refused and still insisted upon going.
We may ask why Pharaoh tried to restrain Hadad? When Hadad left, Pharaoh could repossess the land that he had given him. It is also possible that the queen did not want to lose close contact with her sister and nephew. A third possibility is that Pharaoh foresaw (and wished to prevent) future conflict between Hadad and the new king of Israel, Solomon, who by this time may have already been married to Pharaoh’s daughter.
21 Lorsque Hadad apprit en Egypte que David était couché avec ses pères, et que Joab, chef de l'armée, était mort, il dit à Pharaon: Laisse-moi aller dans mon pays.