Adam Clarke Bible Commentary
Let that day be darkness - The meaning is exactly the same with our expression, "Let it be blotted out of the calendar." However distinguished it may have been, as the birthday of a man once celebrated for his possessions, liberality, and piety, let it no longer be thus noted; as he who was thus celebrated is now the sport of adversity, the most impoverished, most afflicted, and most wretched of human beings.
Let not God regard it from above - אל ידרשהו al yidreshehu, "Let Him not require it" - let Him not consider it essential to the completion of the days of the year; and therefore he adds, neither let the light shine upon it. If it must be a part of duration, let it not be distinguished by the light of the sun.
John Gill Bible Commentary
Let that day be darkness,.... Not only dark, but darkness itself, extremely dark; and which is to be understood not figuratively of the darkness of affliction and calamity; this Job would not wish for, either for himself, who had enough of that, or for others; but literally of gross natural darkness, that was horrible and dreadful, as some (x) render it: this was the reverse of what God said at the creation, "let there be light", Gen 1:3, and there was, and he called it day; but Job wishes his day might be darkness, as the night; either that it had been always dark, and never become day, or in its return be remarkably dark and gloomy:
let not God regard it, from above; that is, either God who is above, and on high, the High and Holy One, the Most High God, and who is higher than the highest, and so this is a descriptive character of him; or else this respects the place where he is, the highest heaven, where is his throne, and from whence he looks and takes notice of the sons of men, and of all things done below: and this wish must be understood consistent with his omniscience, who sees and knows all persons and things, even what are done in the dark, and in the darkest days; for the darkness and the light are alike to him; and as consistent with his providence, which is continually exercised about persons and things on earth without any intermission, even on every day in the year; and was it to cease one day, hour, or moment, all would be dissolved, and be thrown into the utmost confusion and disorder: but Job means the smiles of his providence, which he wishes might be restrained on this day; that he would not cause his sun in the heavens to shine out upon it, nor send down gentle and refreshing showers of rain on it; in which sense he is said to care for and regard the land of Canaan, Deu 11:11; where the same word is used as here; or the sense is, let it be so expunged from the days of the year, the when it is sought for, and if even it should be by God himself, let it not be found; or let him not "seek" (y) after it, to do any good upon it:
neither let the light shine upon it; the light of the sun, or the morning light, as the Targum, much less the light at noonday; even not the diurnal light, as Schmidt interprets it, in any part of the day: light is God's creature, and very delightful and desirable; the best things, and the most comfortable enjoyments, whether temporal, spiritual, or eternal, are expressed by it; and, on the other hand, a state of darkness is the most uncomfortable, and therefore the worst and most dismal things and states are signified by it.
(x) "horrens", Caligo, Schultens. (y) "ne requirat", Montanus, &c.