After this - Dr. Good renders this, "at length." It means after the long silence of his friends, and after he saw that there was no prospect of relief or of consolation.
Opened Job his mouth - The usual formula in Hebrew to denote thc commencement of a speech; see Matthew 5:2. Schultens contends that it means boldness and vehemency of speech, παῤῥησία parrēsia, or an opening of the mouth for the purpose of accusing, expostulating, or complaining; or to begin to utter some sententious, profound, or sublime maxim; and in support of this he appeals to Psalm 78:2, ard Proverbs 8:6. There is probably, however nothing more intended than to begin to speak. It is in accordance with Oriental views, where an act of speaking is regarded as a grave and important matter, and is entered on with much deliberation. Blackwell (Life of Homer, p. 43) remarks that the Turks, Arabs, Hindoos, and the Orientals in general, have little inclination to society and to general conversation, that they seldom speak, and that their speeches are sententious and brief, unless they are much excited. With such men, to make a speech is a serious matter, as is indicated by the manner in which their discourses are commonly introduced: "I will open my mouth," or they "opened the mouth," implying great deliberation and gravity. This phrase occurs often in Homer, Hesiod, Orpheus, and in Virgil (compare Aeneid vi. 75), as well as in the Bible. See Burder, in Rosenmuller's Morgenland, "in loc."
And cursed his day - The word rendered "curse" here, קלל qâlal is different from that used in Job 1:11; Job 2:9. It is the proper word to denote "to curse." The Syriac adds, "the day in which he was born." A similar expression occurs in Klopstock's Messias, Ges. iii.
Wenn nun, aller Kinder beraubt, die verzweifelude Mutter,
Wuthend dem Tag. an dem sie gebahr, und gebohren ward, fluchet.
"When now of all her children robbed, the desperate mother enraged
Curses the day in which she bare, and was borne."

After this opened Job his mouth - After the seven days' mourning was over, there being no prospect of relief, Job is represented as thus cursing the day of his birth. Here the poetic part of the book begins; for most certainly there is nothing in the preceding chapters either in the form or spirit of Hebrew poetry. It is easy indeed to break the sentences into hemistichs; but this does not constitute them poetry: for, although Hebrew poetry is in general in hemistichs, yet it does not follow that the division of narrative into hemistichs must necessarily constitute it poetry.
In many cases the Asiatic poets introduce their compositions with prose narrative; and having in this way prepared the reader for what he is to expect, begin their deevans, cassidehs, gazels, etc. This appears to be the plan followed by the author of this book. Those who still think, after examining the structure of those chapters, and comparing them with the undoubted poetic parts of the book, that they also, and the ten concluding verses, are poetry, have my consent, while I take the liberty to believe most decidedly the opposite.
Cursed his day - That is, the day of his birth; and thus he gave vent to the agonies of his soul, and the distractions of his mind. His execrations have something in them awfully solemn, tremendously deep, and strikingly sublime. But let us not excuse all the things which he said in his haste, and in the bitterness of his soul, because of his former well established character of patience. He bore all his privations with becoming resignation to the Divine will and providence: but now, feeling himself the subject of continual sufferings, being in heaviness through manifold temptation, and probably having the light of God withdrawn from his mind, as his consolations most undoubtedly were, he regrets that ever he was born; and in a very high strain of impassioned poetry curses his day. We find a similar execration to this in Jeremiah, Jeremiah 20:14-18, and in other places; which, by the way, are no proofs that the one borrowed from the other; but that this was the common mode of Asiatic thinking, speaking, and feeling, on such occasions.

After this opened (a) Job his mouth, and (b) cursed his day.
(a) The seven days ended, (Job 2:13).
(b) Here Job begins to feel his great imperfection in this battle between the spirit and the flesh, (Romans 7:18) and after a manner yields yet in the end he gets victory though he was in the mean time greatly wounded.

After this opened Job his mouth,.... order to speak, and began to speak of his troubles and afflictions, and the sense he had of them; for though, this phrase may sometimes signify to speak aloud, clearly and distinctly, and with great freedom and boldness, yet here it seems to design no more than beginning to speak, or breaking silence after it had been long kept: be spake after his first trial and blessed the name of the Lord, and upon his second, and reproved his wife for her foolish speaking; but upon the visit of his three friends, and during the space of seven days, a profound silence was kept by him and them; and when he perceived that they chose not to speak to him, and perhaps his distemper also decreased, and his pain somewhat abated, he broke out into the following expressions:
and cursed his day: he did not curse his God, as Satan said he would, and his wife advised him to: nor did he curse his fellow creatures, or his friends, as wicked men in passion are apt to do, nor did he curse himself, as profane persons often do, when any evil befalls them; but he cursed his day; not the day on which his troubles came upon him, for there were more than one, and they were still continued, but the day of his birth, as appears from Job 3:3; and so the Syriac and Arabic versions add here, "in which he was born"; and what is meant by cursing it may be learnt from his own words in the following verses, the substance of which is, that he wished either it had never been, or he had never been born; but since that was impossible, that it might be forgotten, and never observed or had in esteem, but be buried oblivion and obscurity, and be branded with a black mark, as an unhappy day, for ever: the word (s) signifies, he made light of it, and spoke slightly and contemptibly of it; he disesteemed it, yea, detested it, and could not bear to think of it, and desired that it might be disrespected by God and men; so that there is no need of such questions, whether it is in the power of man to curse? and whether it is lawful to curse the creature? and whether a day is capable of a curse? The frame of mind in which Job was when he uttered these words is differently represented; some of the Jewish writers will have it that he denied the providence of God, and thought that all things depended upon the stars, or planets which rule on the day a man is born, and therefore cursed his stars; whereas nothing is more evident than that Job ascribes all that befell him to the purpose and providence of God, Job 23:14; some say he was in the utmost despair, and had no hope of eternal life and salvation, but the contrary to this is clear from Job 13:15; and many think he had lost all patience, for which he was so famous; but if he had, he would not have been so highly spoken of as he is in James 5:11; it is true indeed there may be a mixture of weakness with respect to the exercise of that grace at this time, and which may appear in some after expressions of his; yet were it not for these and the like, as we could not have such an idea of his sorrows and afflictions, and of that quick sense and perception he had of them, so neither of his exceeding great patience in enduring them as he did; and, besides, what impatience he was guilty of was not only graciously forgiven, but he through the grace of God was enabled to conquer; and patience had its perfect work in him, and he persevered therein to the end; though after all he is not to be excused of weakness and infirmity, since he is blamed not only by Elihu, but by the Lord himself; yea, Job himself owned his sin and folly, and repented of it, Job 40:4.
(s) "Opponitur verbum" "verbo" "significat se pronunciasse diem inglorium", Codurcus.

For seven days Job's friends sat by him in silence, without offering consolidation: at the same time Satan assaulted his mind to shake his confidence, and to fill him with hard thoughts of God. The permission seems to have extended to this, as well as to torturing the body. Job was an especial type of Christ, whose inward sufferings, both in the garden and on the cross, were the most dreadful; and arose in a great degree from the assaults of Satan in that hour of darkness. These inward trials show the reason of the change that took place in Job's conduct, from entire submission to the will of God, to the impatience which appears here, and in other parts of the book. The believer, who knows that a few drops of this bitter cup are more dreadful than the sharpest outward afflictions, while he is favoured with a sweet sense of the love and presence of God, will not be surprised to find that Job proved a man of like passions with others; but will rejoice that Satan was disappointed, and could not prove him a hypocrite; for though he cursed the day of his birth, he did not curse his God. Job doubtless was afterwards ashamed of these wishes, and we may suppose what must be his judgment of them now he is in everlasting happiness.

JOB CURSES THE DAY OF HIS BIRTH AND WISHES FOR DEATH. (Job 3:1-19)
opened his mouth--The Orientals speak seldom, and then sententiously; hence this formula expressing deliberation and gravity (Psalm 78:2). He formally began.
cursed his day--the strict Hebrew word for "cursing:" not the same as in Job 1:5. Job cursed his birthday, but not his God.

Job's first longer utterance now commences, by which he involved himself in the conflict, which is his seventh temptation or trial.
1, 2 After this Job opened his mouth, and cursed his day. And Job spake, and said.

His day - His birth - day, in vain do some endeavour to excuse this and the following speeches of Job, who afterwards is reproved by God, and severely accuseth himself for them, Job 38:2, Job 40:4, Job 13:3, Job 13:6. And yet he does not proceed so far as to curse God, but makes the devil a liar: but although he does not break forth into direct reproaches of God, yet he makes indirect reflections upon his providence. His curse was sinful, both because it was vain, being applied to a thing, which was not capable of blessing and cursing, and because it cast a blame upon God for bringing that day, and for giving him life on that day.