Ecclesiastes 3:12
12. in them—in God's works (Ec 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 (Ga 6:9, 10). Not sensual joy and self-indulgence (Php 4:4; Jas 4:16, 17).
Ecclesiastes 3:22
22. (Compare Ec 3:12; 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 (Ec 11:9); not as the anxious money-seeker (Ec 2:23; 5:10-17).
his portion—in the present life. If it were made his main portion, it would be "vanity" (Ec 2:1; Lu 16:25). for who, &c.—Our ignorance as to the future, which is God's "time" (Ec 3:11), should lead us to use the present time in the best sense and leave the future to His infinite wisdom (Mt 6:20, 25, 31-34).Ecclesiastes 5:18-19
18. Returns to the sentiment (Ec 3:12, 13, 22); translate: "Behold the good which I have seen, and which is becoming" (in a man).
which God giveth—namely, both the good of his labor and his life. his portion—legitimately. It is God's gift that makes it so when regarded as such. Such a one will use, not abuse, earthly things (1Co 7:31). Opposed to the anxious life of the covetous (Ec 5:10, 17).19. As Ec 5:18 refers to the "laboring" man (Ec 5:12), so Ec 5:19 to the "rich" man, who gets wealth not by "oppression" (Ec 5:8), but by "God's gift." He is distinguished also from the "rich" man (Ec 6:2) in having received by God's gift not only "wealth," but also "power to eat thereof," which that one has not.
to take his portion—limits him to the lawful use of wealth, not keeping back from God His portion while enjoying his own.