Malbim on Job 42:10

(י-יב) וה', ובזכות זה שמחל על עלבונו והתפלל בעדם, באתהו טובה שלא לבד ששב את שבותו, כי גם הוסיף את כל אשר לאיוב למשנה, וכפי הנראה מחז"ל לא נשללו הקנינים ולא מתו בניו רק השטן הסתירם מנגד פניו ושלח אליו מלאך לבשרו הבשורות הרעות, וכל קניניו ובניו היו כל משך זמן ההוא ביד השטן, ועז"א את כל אשר לאיוב כי היו הקנינים הקודמים, ועתה הוסיף עליהם עד שהיו למשנה, וכמו שמפרש שהיה לו ארבעה עשר אלף צאן וכו' הכל כפול מהקודם: Despite the terrible things they had said of him, Job intercedes with God on behalf of his three companions, just as he had in the past for his own children, and their offering is accepted. In reward for this generosity of spirit, God restored all Job’s losses and even doubled his fortune.
The book ends with God’s reconfirmation of Job’s virtue and integrity. All his losses are restored,¹Nahmanides suggests that Job's children had not really been killed nor had his possessions actually been destroyed. They had all only been hidden from him by Satan who had sent the messengers with news of their loss. His children and possessions are now restored to him. The former are endowed with still greater beauty and the number of the latter is doubled. his friends and family are reconciled and Job lives out the rest of his long life in peace and contentment.