A.T. Robertson Commentary James 3:18

"And the fruit of righteousness is sown in peace for them that make peace." — James 3:18 (ASV)

Is sown in peace (εν ειρηνη σπειρετα). Present passive indicative of σπειρω, to sow. The seed which bears the fruit is sown, but James catches up the metaphor of καρπος (fruit) from verse 17. Only in peace is the fruit of righteousness found.

For them that make peace (τοις ποιουσιν ειρηνην). Dative case of the articular participle of ποιεω. See Eph 2:15 for this phrase (doing peace), and Col 1:20 for ειρηνοποιεω, of Christ, and Mt 5:9 for ειρηνοποιο (peacemakers). Only those who act peaceably are entitled to peace.