Якова 3:18

"The peaceable fruit of righteousness." He says "righteousness"; because it is itself the true wisdom. As in the case of the earthly wisdom, after the characteristic description came its results; so in this verse, in the case of the heavenly wisdom. There the results were present; here, future. fruit . . . sown--Compare Psa 97:11; Isa 61:3, "trees of righteousness." Anticipatory, that is, the seed whose "fruit," namely, "righteousness," shall be ultimately reaped, is now "sown in peace." "Righteousness," now in germ, when fully developed as "fruit" shall be itself the everlasting reward of the righteous. As "sowing in peace" (compare "sown in dishonor," Co1 15:43) produces the "fruit of righteousness," so conversely "the work" and "effect of righteousness" is "peace." of them that make peace--"by (implying also that it is for them, and to their good) them that work peace." They, and they alone, are "blessed." "Peacemakers," not merely they who reconcile others, but who work peace. "Cultivate peace" [ESTIUS]. Those truly wise towards God, while peaceable and tolerant towards their neighbors, yet make it their chief concern to sow righteousness, not cloaking men's sins, but reproving them with such peaceable moderation as to be the physicians, rather than the executioners, of sinners [CALVIN]. Next: James Chapter 4

The apostle here reproves ambition, and an arrogant magisterial tongue; and shows the duty and advantage of bridling it because of its power to do mischief. Those who profess religion ought especially to govern their tongues (Jam 3:1-12). True wisdom makes men meek, and avoiders of strife and envy: and hereby it may easily be distinguished from a wisdom that is earthly and hypocritical (Jam 3:13 to the end).

3:18 James uses an agricultural image to emphasize the benefits of living by the wisdom from above: Those who plant seeds of peace in relationships will enjoy a luxuriant harvest of righteousness in those relationships (cp. Matt 5:9).