I will give comments from some great commentators
St. Thomas Aquinas- For God does not totally expose his servants to the will of Satan, but according to a fitting measure, as St. Paul says in 1 Cor., “The faithful God does not suffer you to be tempted beyond what you can endure.” (10:13)
**St. Gregory the Great- ** Here again, the safeguard of protection goes along with the permission to smite, and the dispensation of God both while guarding, forsakes his elect servant, and while forsaking, guards him. A portion of him He gives over, a portion He protects. For if he had left Job wholly in the hand of so dire a foe, what could have become of a mere man? And so with the very justice of the permission there is mixed a certain measure of pity, that in one and the same contest, both His lowly servant might rise by oppression, and the towering enemy be brought down by the permission. Thus the holy man is given over to the adversary’s hand, but yet in his inmost soul he is held fast by the hand of his Helper. For he was of the number of those sheep, concerning whom Truth itself said in the Gospel, Neither shall any man pluck them out of My hand. [John 10, 28] And yet it is said to the enemy, when he demands him, Behold, he is in thine hand. The same man then is at the same time in the hand of God, and in the hand of the devil. For by saying, he is in thine hand, and straightway adding, but save his life, the pitiful Helper openly shewed that His hand was upon him whom He yielded up, and that in giving He did not give him, whom, while He cast him forth, He at the same time hid from the darts of his adversary.
St. John Chrysostom- that is, do not do away with him. So it is possible for him if he gets permission. If you do away with him, we shall no longer be able to applaud the spectacle. So he can do away with a man but he cannot make him bad. See, from this we learn that the devil envies the good, that though envying them he cannot attack them until God permits it. God often permits it, but not in all respects, sometimes affecting possessions, sometimes bodily things, which suggests his receiving authorization a second time. Let us learn from this that it is with permission that he can do all he can do, that even if defeated, he does not desist; he keeps trying further things. It is up to God, however, to allow him or not to allow; why did he not say, Only, do not touch his life, but Only, spare his life? He enveloped him in a deep dread.