Gregory the Dialogist

But Job lived after these scourges a hundred and forty years, and saw his sons, and his sons' sons, even to the fourth generation, and he died an old man, and full of days. 47. In Holy Scripture a person is not easily recorded as 'full of days,' unless he is one whose conduct is praised in the same Scripture. For he is in truth void of days, who, even if he has lived ever so long, has wasted the time of his life in vanity. …

Morals on the Book of Job, Book XXXV ↗

Thomas Aquinas

Since Job also had been scourged in his own body, he is given length of days to increase his prosperity, and so the text goes on, "But Job lived after his trials one hundred and forty years." So that we may understand that he lived the whole time in prosperity the text says, "and he saw his children and his children's children up to the fourth generation."

Commentary on Job ↗