A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
ecc 3:1(Ecc. 3:1-22)
Man has his appointed cycle of seasons and vicissitudes, as the sun, wind, and water (Ecc 1:5-7).
purpose--as there is a fixed "season" in God's "purposes" (for example, He has fixed the "time" when man is "to be born," and "to die," Ecc 3:2), so there is a lawful "time" for man to carry out his "purposes" and inclinations. God does not condemn, but approves of, the use of earthly blessings (Ecc 3:12); it is the abuse that He condemns, the making them the chief end (Co1 7:31). The earth, without human desires, love, taste, joy, sorrow, would be a dreary waste, without water; but, on the other hand, the misplacing and excess of them, as of a flood, need control. Reason and revelation are given to control them.
ecc 3:2time to die-- (Psa 31:15; Heb 9:27).
plant--A man can no more reverse the times and order of "planting," and of "digging up," and transplanting, than he can alter the times fixed for his "birth" and "death." To try to "plant" out of season is vanity, however good in season; so to make earthly things the chief end is vanity, however good they be in order and season. GILL takes it, not so well, figuratively (Jer 18:7, Jer 18:9; Amo 9:15; Mat 15:13).
ecc 3:3time to kill--namely, judicially, criminals; or, in wars of self-defense; not in malice. Out of this time and order, killing is murder.
to heal--God has His times for "healing" (literally, Isa 38:5, Isa 38:21; figuratively, Deu 32:39; Hos 6:1; spiritually, Psa 147:3; Isa 57:19). To heal spiritually, before the sinner feels his wound, would be "out of time," and so injurious.
time to break down--cities, as Jerusalem, by Nebuchadnezzar.
build up--as Jerusalem, in the time of Zerubbabel; spiritually (Amo 9:11), "the set time" (Psa 102:13-16).
ecc 3:4mourn--namely, for the dead (Gen 23:2).
dance--as David before the ark (Sa2 6:12-14; Psa 30:11); spiritually (Mat 9:15; Luk 6:21; Luk 15:25). The Pharisees, by requiring sadness out of time, erred seriously.
ecc 3:5cast away stones--as out of a garden or vineyard (Isa 5:2).
gather--for building; figuratively, the Gentiles, once castaway stones, were in due time made parts of the spiritual building (Eph 2:19-20), and children of Abraham (Mat 3:9); so the restored Jews hereafter (Psa 102:13-14; Zac 9:16).
refrain . . . embracing-- (Joe 2:16; Co1 7:5-6).
ecc 3:6time to get--for example, to gain honestly a livelihood (Eph 4:23).
lose--When God wills losses to us, then is our time to be content.
keep--not to give to the idle beggar (Th2 3:10).
cast away--in charity (Pro 11:24); or to part with the dearest object, rather than the soul (Mar 9:43). To be careful is right in its place, but not when it comes between us and Jesus Christ (Luk 10:40-42).
ecc 3:7rend--garments, in mourning (Joe 2:13); figuratively, nations, as Israel from Judah, already foretold, in Solomon's time (Kg1 11:30-31), to be "sewed" together hereafter (Eze 37:15, Eze 37:22).
silence-- (Amo 5:13), in a national calamity, or that of a friend (Job 2:13); also not to murmur under God's visitation (Lev 10:3; Psa 39:1-2, Psa 39:9).
ecc 3:8hate--for example, sin, lusts (Luk 14:26); that is, to love God so much more as to seem in comparison to hate "father or mother," when coming between us and God.
a time of war . . . peace-- (Luk 14:31).
ecc 3:9But these earthly pursuits, while lawful in their season, are "unprofitable" when made by man, what God never intended them to be, the chief good. Solomon had tried to create an artificial forced joy, at times when he ought rather to have been serious; the result, therefore, of his labor to be happy, out of God's order, was disappointment. "A time to plant" (Ecc 3:2) refers to his planting (Ecc 2:5); "laugh" (Ecc 3:4), to Ecc 2:1-2; "his mirth," "laughter"; "build up," "gather stones" (Ecc 3:3, Ecc 3:5), to his "building" (Ecc 2:4); "embrace," "love," to his "princess" (see on Ecc 2:8); "get" (perhaps also "gather," Ecc 3:5-6), to his "gathering" (Ecc 2:8). All these were of "no profit," because not in God's time and order of bestowing happiness.
ecc 3:10(See on Ecc 1:13).
ecc 3:11his time--that is, in its proper season (Psa 1:3), opposed to worldlings putting earthly pursuits out of their proper time and place (see on Ecc 3:9).
set the world in their heart--given them capacities to understand the world of nature as reflecting God's wisdom in its beautiful order and times (Rom 1:19-20). "Everything" answers to "world," in the parallelism.
so that--that is, but in such a manner that man only sees a portion, not the whole "from beginning to end" (Ecc 8:17; Job 26:14; Rom 11:33; Rev 15:4). PARKHURST, for "world," translates: "Yet He hath put obscurity in the midst of them," literally, "a secret," so man's mental dimness of sight as to the full mystery of God's works. So HOLDEN and WEISS. This incapacity for "finding out" (comprehending) God's work is chiefly the fruit of the fall. The worldling ever since, not knowing God's time and order, labors in vain, because out of time and place.
ecc 3:12in them--in God's works (Ecc 3:11), as far as relates to man's duty. Man cannot fully comprehend them, but he ought joyfully to receive ("rejoice in") God's gifts, and "do good" with them to himself and to others. This is never out of season (Gal 6:9-10). Not sensual joy and self-indulgence (Phi 4:4; Jam 4:16-17).
ecc 3:13Literally, "And also as to every man who eats . . . this is the gift of God" (Ecc 3:22; Ecc 5:18). When received as God's gifts, and to God's glory, the good things of life are enjoyed in their due time and order (Act 2:46; Co1 10:31; Ti1 4:3-4).
ecc 3:14(Sa1 3:12; Sa2 23:5; Psa 89:34; Mat 24:35; Jam 1:17).
for ever--as opposed to man's perishing labors (Ecc 2:15-18).
any thing taken from it--opposed to man's "crooked and wanting" works (Ecc 1:15; Ecc 7:13). The event of man's labors depends wholly on God's immutable purpose. Man's part, therefore, is to do and enjoy every earthly thing in its proper season (Ecc 3:12-13), not setting aside God's order, but observing deep reverence towards God; for the mysteriousness and unchangeableness of God's purposes are designed to lead "man to fear before Him." Man knows not the event of each act: otherwise he would think himself independent of God.
ecc 3:15Resumption of Ecc 1:9. Whatever changes there be, the succession of events is ordered by God's "everlasting" laws (Ecc 3:14), and returns in a fixed cycle.
requireth that . . . past--After many changes, God's law requires the return of the same cycle of events, as in the past, literally, "that which is driven on." The Septuagint and Syriac translate: "God requireth (that is, avengeth) the persecuted man"; a transition to Ecc 3:16-17. The parallel clauses of the verse support English Version.
ecc 3:16Here a difficulty is suggested. If God "requires" events to move in their perpetual cycle, why are the wicked allowed to deal unrighteously in the place where injustice ought least of all to be; namely, "the place of judgment" (Jer 12:1)?
ecc 3:17Solution of it. There is a coming judgment in which God will vindicate His righteous ways. The sinner's "time" of his unrighteous "work" is short. God also has His "time" and "work" of judgment; and, meanwhile, is overruling, for good at last, what seems now dark. Man cannot now "find out" the plan of God's ways (Ecc 3:11; Psa 97:2). If judgment instantly followed every sin, there would be no scope for free will, faith, and perseverance of saints in spite of difficulties. The previous darkness will make the light at last the more glorious.
there-- (Job 3:17-19) in eternity, in the presence of the Divine Judge, opposed to the "there," in the human place of judgment (Ecc 3:16): so "from thence" (Gen 49:24).
ecc 3:18estate--The estate of fallen man is so ordered (these wrongs are permitted), that God might "manifest," that is, thereby prove them, and that they might themselves see their mortal frailty, like that of the beasts.
sons of men--rather, "sons of Adam," a phrase used for "fallen men." The toleration of injustice until the judgment is designed to "manifest" men's characters in their fallen state, to see whether the oppressed will bear themselves aright amidst their wrongs, knowing that the time is short, and there is a coming judgment. The oppressed share in death, but the comparison to "beasts" applies especially to the ungodly oppressors (Psa 49:12, Psa 49:20). They too need to be "manifested" ("proved"), whether, considering that they must soon die as the "beasts," and fearing the judgment to come, they will repent (Dan 4:27).
ecc 3:19Literally, "For the sons of men (Adam) are a mere chance, as also the beast is a mere chance." These words can only be the sentiments of the skeptical oppressors. God's delay in judgment gives scope for the "manifestation" of their infidelity (Ecc 8:11; Psa 55:19; Pe2 3:3,4). They are "brute beasts," morally (Ecc 3:18; Jde 1:10); and they end by maintaining that man, physically, has no pre-eminence over the beast, both alike being "fortuities." Probably this was the language of Solomon himself in his apostasy. He answers it in Ecc 3:21. If Ecc 3:19-20 be his words, they express only that as regards liability to death, excluding the future judgment, as the skeptic oppressors do, man is on a level with the beast. Life is "vanity," if regarded independently of religion. But Ecc 3:21 points out the vast difference between them in respect to the future destiny; also (Ecc 3:17) beasts have no "judgment" to come.
ecc 3:21Who knoweth--Not doubt of the destination of man's spirit (Ecc 12:7); but "how few, by reason of the outward mortality to which man is as liable as the beast and which is the ground of the skeptic's argument, comprehend the wide difference between man and the beast" (Isa 53:1). The Hebrew expresses the difference strongly, "The spirit of man that ascends, it belongeth to on high; but the spirit of the beast that descends, it belongeth to below, even to the earth." Their destinations and proper element differ utterly [WEISS].
ecc 3:22(Compare Ecc 3:12; Ecc 5:18). Inculcating a thankful enjoyment of God's gifts, and a cheerful discharge of man's duties, founded on fear of God; not as the sensualist (Ecc 11:9); not as the anxious money-seeker (Ecc 2:23; Ecc 5:10-17).
his portion--in the present life. If it were made his main portion, it would be "vanity" (Ecc 2:1; Luk 16:25).
for who, &c.--Our ignorance as to the future, which is God's "time" (Ecc 3:11), should lead us to use the present time in the best sense and leave the future to His infinite wisdom (Mat 6:20, Mat 6:25, Mat 6:31-34).