Tafsiran Ayub 42:10: Rashi & Malbim

Now the Lord returned Job’s captivity when he prayed [The word] שָׁב is inappropriate in this matter, and it is as though it were written: “And He returned (נשאתי) Job’s captivity when he prayed.”

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.

for his friend In the merit that he prayed for each friend of his.

twice as much Heb. למשנה, for one, two; and Scripture was not exact in its wording.