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 5:18
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). Ecclesiastes 7:18
18. this . . . this—the two opposite excesses (Ec 7:16, 17), fanatical, self-wise righteousness, and presumptuous, foolhardy wickedness.
he that feareth God shall come forth of them all—shall escape all such extremes (Pr 3:7). Ecclesiastes 9:7
7. Addressed to the "righteous wise," spoken of in Ec 9:1. Being "in the hand of God," who now accepteth "thy works" in His service, as He has previously accepted thy person (Ge 4:4), thou mayest "eat . . . with a cheerful (not sensually 'merry') heart" (Ec 3:13; 5:18; Ac 2:46).