Hast thou commanded the morning since thy days - That is, in thy lifetime hast thou ordered the light of the morning to shine, and directed its beams over the world? God appeals to this as one of the proofs of his majesty and power - and who can look upon the spreading light of the morning and be insensible to the force and beauty of the appeal? The transition from the ocean to the morning may have been partly because the light of the morning is one of the striking exhibitions of the power of God, and partly because in the creation of the world the light of the sun was made to dawn soon after the gathering together of the waters into seas; see Genesis 1:10, Genesis 1:14. The phrase "since thy days," implies that the laws determining the rising of the sun were fixed long before the time of Job. It is asked whether this had been done since he had an existence, and whether he had an agency in effecting it - implying that it was an ancient and established ordinance long before he was born.
Caused the day-spring to know his place - The day-spring (שׁחר shachar) means the "aurora, the dawn, the morning." The mention of its "place" here seems to be an allusion to the fact that it does not always occupy the same position. At one season of the year it appears on the equator, at another north, and at another south of it, and is constantly varying its position. Yet it always knows its place. It never fails to appear where by the long-observed laws it ought to appear. It is regular in its motions, and is evidently under the control of an intelligent Being, who has fixed the laws of its appearing.

Hast thou commanded the morning - This refers to dawn or morning twilight, occasioned by the refraction of the solar rays by means of the atmosphere; so that we receive the light by degrees, which would otherwise burst at once upon our eyes, and injure, if not destroy, our sight; and by which even the body of the sun himself becomes evident several minutes before he rises above the horizon.
Caused the dayspring to know his place - This seems to refer to the different points in which daybreak appears during the course of the earth's revolution in its orbit; and which variety of points of appearing depends on this annual revolution. For, as the earth goes round the sun every year in the ecliptic, one half of which is on the north side of the equinoctial, and the other half on its south side, the sun appears to change his place every day. These are matters which the wisdom of God alone could plan, and which his power alone could execute. It may be just necessary to observe that the dawn does not appear, nor the sun rise exactly in the same point of the horizon, two successive days in the whole year, as he declines forty-three degrees north, and forty-three degrees south, of east; beginning on the 21st of March, and ending on the 22d of December; which variations not only produce the places of rising and setting, but also the length of day and night. And by this declination north and south, or approach to and recession from the tropics of Cancer and Capricorn, the solar light takes hold of the ends of the earth, Job 38:13, enlightens the arctic and antarctic circles in such a way as it would not do were it always on the equinoctial line; these tropics taking the sun twenty-three and a half degrees north, and as many south, of this line.

Hast thou commanded the (i) morning since thy days; [and] caused the dayspring to know his place;
(i) That is, to rise, since you were born?

Hast thou commanded the morning since thy days;.... Job had lived to see many a morning, but it never was in his power to command one; he had been in such circumstances as to wish for morning light before it was, but was obliged to wait for it, could not hasten it, or cause it to spring before its time; see Job 7:3; one of the Targums is,
"wast thou in the days of the first creation, and commandedst the morning to be?''
he was not, God was; he was before the first morning, and commanded it into being, Genesis 1:3;
and caused the dayspring to know his place; the first spring of light or dawn of day; which though it has a different place every day in the year, as the sun ascends or descends in the signs of the Zodiac, yet it knows and observes its exact place, being taught of God.

The Lord questions Job, to convince him of his ignorance, and shame him for his folly in prescribing to God. If we thus try ourselves, we shall soon be brought to own that what we know is nothing in comparison with what we know not. By the tender mercy of our God, the Day-spring from on high has visited us, to give light to those that sit in darkness, whose hearts are turned to it as clay to the seal, 2-Corinthians 4:6. God's way in the government of the world is said to be in the sea; this means, that it is hid from us. Let us make sure that the gates of heaven shall be opened to us on the other side of death, and then we need not fear the opening of the gates of death. It is presumptuous for us, who perceive not the breadth of the earth, to dive into the depth of God's counsels. We should neither in the brightest noon count upon perpetual day, nor in the darkest midnight despair of the return of the morning; and this applies to our inward as well as to our outward condition. What folly it is to strive against God! How much is it our interest to seek peace with him, and to keep in his love!

Passing from creation to phenomena in the existing inanimate world.
Hast thou--as God daily does.
commanded the morning--to rise.
since thy days--since thou hast come into being.
his place--It varies in its place of rising from day to day, and yet it has its place each day according to fixed laws.

12 Hast thou in thy life commanded a morning,
Caused the dawn to know its place,
13 That it may take hold of the ends of the earth,
So that the evil-doers are shaken under it?
14 That it changeth like the clay of a signet-ring,
And everything fashioneth itself as a garment.
15 Their light is removed from the evil-doers,
And the out-stretched arm is broken.
The dawn of the morning, spreading out from one point, takes hold of the carpet of the earth as it were by the edges, and shakes off from it the evil-doers, who had laid themselves to rest upon it the night before. נער, combining in itself the significations to thrust and to shake, has the latter here, as in the Arab. nâ‛ûra, a water-wheel, which fills its compartments below in the river, to empty them out above. Instead of ידּעתּה שׁחר with He otians, the Keri substitutes ידּעתּ השׁחר. The earth is the subj. to Job 38:14: the dawn is like the signet-ring, which stamps a definite impress on the earth as the clay, the forms which floated in the darkness of the night become visible and distinguishable. The subj. to Job 38:14 are not morning and dawn (Schult.), still less the ends of the earth (Ew. with the conjecture: יתיבצו, "they become dazzlingly white"), but the single objects on the earth: the light of morning gives to everything its peculiar garb of light, so that, hitherto overlaid by a uniform darkness, they now come forth independently, they gradually appear in their variegated diversity of form and hue. In כּמו לבוּשׁ, לבוש is conceived as accusative (Arab. kemâ libâsan, or thauban), while in כלבושׁ (Psalm 104:6, instar vestis) it would be genitive. To the end of the strophe everything is under the logical government of the ל of purpose in Job 38:13. The light of the evil-doers is, according to Job 24:17, the darkness of the night, which is for them in connection with their works what the light of day is for other men. The sunrise deprives them, the enemies of light in the true sense (Job 24:13), of this light per antiphrasin, and the carrying out of their evil work, already prepared for, is frustrated. The ע of רשׁעים, Job 38:13 and Job 38:15, is תלויה עין [Ayin suspensum,] which is explained according to the Midrash thus: the רשׁעים, now עשׁירים (rich), become at a future time רשׁים (poor); or: God deprives them of the עין (light of the eye), by abandoning them to the darkness which they loved.

Morning - Didst thou create the sun, and appoint the order and succession of day and night. Since - Since thou wast born: this work was done long before thou wast born. To know - To observe the punctual time when, and the point of the heavens where it should arise; which varies every day.