20 Are not my days few? cease then, and let me alone, that I may take comfort a little,
[AD 398] Didymus the Blind on Job 10:18-22
Someone could think that Job’s statement comes from desperation, but that is proven wrong by what God has said: “Do you believe I treated you like this for any other reason than to reveal your righteousness?” Job, who previously had said, “If I am wicked, woe to me,” does not contradict this assumption but reveals the bitterness of life. An evil person would not do that, for he rejoices in this [life]. Above all, Job wants to reveal to his friends the reason why he did not die at the moment of his birth, namely, because he was to be an example of energy and strength. According to a different interpretation, even the life in the flesh is indicated, about which Paul writes, “If for this life only we have hoped in Christ, we are of all people most to be pitied.” Job experiences the pleasant as well as the bitter sides of life; no one who has rid himself of the flesh rejoices in wealth or excess, nor is he plagued by hardship. Job has tasted this life and its pleasures, for he was blessed with many good children and was rich and healthy. But since his situation turned into its opposite, he also experienced the reverse of his previous life and acknowledged in real life the vanity of these things. This is why Job teaches us not to long for them by saying, “Why did you bring me forth from the womb? Would that I had died before any eye had seen me, and were as though I had not been.”Job expresses this in the form of a prayer, for his burdens were not light and he endured the pains not without feeling them. For it would not have been manful had he not felt his sufferings. But he teaches that he endured the pain with the help of God’s power, by praying in gratefulness. Paul also expresses this: “It was not I, but the grace of God that is with me.”
Job wants to find relief before he has to go from where he cannot return. Therefore, he does not pray for himself, but to teach the friends who think that those who suffer hardship are evil but those who are free from hardship are righteous. He desired that they should gain certainty regarding the divine resolutions about him. One should not assume that Job denies the resurrection of the dead. Rather, Job says, “From where I will not return to lead a mortal life.” Job knows that he will rise as immortal.
Although the brave one was in pain, he talked about the coming age. So he says—not to deny the resurrection—“Before I go from where I will not return.” Job calls the land “a land of gloom and deep darkness, where light is like darkness,” since the holy one ascribes only little to himself. For it would not have been suitable to say, “Before I am in the kingdom of the heavens and in the land of our promises, my God.” Job wants his listener to be instructed about the divine judgment. There has not yet been restitution for deeds done.

[AD 450] Hesychius of Jerusalem on Job 10:18-22
In order to avoid scandalizing many who see his life end in affliction and sadness, it is not without reason that the righteous man asks for the termination of his ordeals. That is why [Job] said, “Before I go, never to return,” evidently, to his human life, as if to say “In fact, if I return down here and receive here the reward of my toils, I will not be worn out and will not renounce the fight to the death in my ordeals. Those who are here, knowing my justice, will see that I receive my reward by coming back here. But if they see me die now in my ordeals, they will either think that Job is wicked or will believe that nothing useful comes from justice.”

[AD 604] Gregory the Dialogist on Job 10:20
Will not the small number of my days be finished in a short time?

He shews himself to live with good heed and circumspection, who, in considering the shortness of the present life does not look to the furtherance but to the ending of it, so as to gather from the end, that all is nought that delights while it is passing. For hence it is said by Solomon, But if a man live many years and rejoice in them all, yet let him remember the time of darkness, and the days that shall be many; and when they come, the past shall be convinced of vanity. Hence again it is written, Whatsoever thou takest in hand, remember thine end, and thou shalt never do amiss. Therefore when sin tempts the mind, it is requisite that the soul should regard the shortness of its gratification, lest iniquity hurry it on to a living death, when it is plain that a mortal life is quickly speeding to an end. But often the eye of our contemplation is bewildered, while our pain is heightened by thickening scourges. It is good to bewail the exile of the present life, yet for mere anguish alone the mind cannot take account of the ills of its blind state. Hence he directly adds, And let me go, that I may bewail my sorrow a little.

For as moderate distress gives vent to tears, so excessive sorrow checks them, since that grief itself is as it were made void of grief, which by swallowing up the mind of the person afflicted, takes away the sense of grief. Therefore the holy man shrinks from being stricken more than he is equal to bear, saying, And let me go, that I may bewail my sorrow a little. As if it were in plain words, 'Qualify the strokes of Thy scourging, that, my pains being made moderate, in weeping I may have power to estimate the miseries I endure.' Which same nevertheless may likewise be understood in another sense. For oftentimes the sinner is so bound by the chains of his wickedness, that he bears indeed the burthen of his sins, and knows not that he is bearing it. Often if he does know with what an amount of guilt he is burthened, he strives to break loose and cannot, so as to hunt it down in himself with free spirit and full conversion. Thus he is unable to 'bewail his sorrow,' for at once he sees the guilt of his sinful state, and by reason of the weight of earthly business, is not at liberty to bewail it. He is unable to 'bewail his sorrow,' who strives indeed to resist evil habits, yet is weighed down by the still increasing desires of the flesh. The presence of this sorrow had inflicted anguish upon the spirit of the Prophet, when he said, My sorrow is continually before me; for I will declare my iniquity, I will be sorry for my sin; but the bands of his sin being loosed, he knew that he was 'let go,' who gave vent to his exultation, saying, Thou hast loosed my bonds, I will offer to Thee the sacrifice of thanksgiving.

Therefore God then 'lets us go' to bewail our sorrow, when He both shews us the evil things that we have done, and helps us to bewail the same, when we know them; He sets our transgressions before our eyes, and with the pitying hand of grace unlooses the bands of the heart, that our soul may lift itself up to liberty for the work of repentance, and loosed from the fetters of the flesh, may with free spirit stretch out towards its Maker the footsteps of love. For it very commonly happens that we the same persons blame our course of life, and yet readily do the very thing that we justly condemn in ourselves. The spirit lifts us up to righteousness, the flesh holds us back to habit; the soul struggles against self-love, but quickly overcome with delight is made captive. Thus it is well said, Let me go that I may bewail my sorrow a little. For except we be 'let go' in mercy from the guilt of sin, with which we are tied and bound, we cannot lament that which we grieve for in ourselves being set against ourselves. But the woe of our guiltiness is then really bewailed, when that dark retribution of the place below is fore-reckoned with lively apprehension.