Albert Barnes Commentary Job 3:1

"After this opened Job his mouth, and cursed his day." — Job 3:1 (ASV)

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 – This is the usual formula in Hebrew to denote the commencement of a speech . Schultens contends that it means boldness and vehemence 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. In support of this, he appeals to Psalm 78:2 and 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 undertaken with much deliberation. Blackwell (Life of Homer, p. 43) remarks that the Turks, Arabs, Hindus, and Orientals in general have little inclination for society and general conversation; they seldom speak, and their speeches are sententious and brief, unless they are much excited. With such people, making a speech is a serious matter, as 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 Virgil , as well as in the Bible. See Burder, in Rosenmuller’s Morgenland, on this passage.

And cursed his day – The word translated “curse” here, קלל qâlal, is different from that used in Job 1:11 and 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, Gesang III.

Wenn nun, aller Kinder beraubt, die verzweifelnde 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 bore, and was born.”