A.T. Robertson Commentary James 3:14

"But if ye have bitter jealousy and faction in your heart, glory not and lie not against the truth." — James 3:14 (ASV)

Bitter jealousy (ζηλον πικρον). Ζηλος occurs in N.T. in good sense (John 2:17) and bad sense (Acts 5:17). Pride of knowledge is evil (1 Corinthians 8:1) and leaves a bitter taste. See "root of bitterness" in Heb 12:14 (cf. Ephesians 4:31). This is a condition of the first class.

Faction (εριθιαν). Late word, from εριθος (hireling, from εριθευω to spin wool), a pushing forward for personal ends, partisanship, as in Php 1:16.

In your heart (εν τη καρδια υμων). The real fountain (πηγη, verse 11).

Glory not (μη κατακαυχασθε). Present middle imperative of κατακαυχαομα, for which see 2:13. Wisdom is essential for the teacher. Boasting arrogance disproves the possession of wisdom.

Lie not against the truth (ψευδεσθε κατα της αληθειας). Present middle imperative of ψευδομα, old verb, to play false, with μη carried over. Lying against the truth is futile. By your conduct do not belie the truth which you teach; a solemn and needed lesson. Cf. Romans 1:18f., 2:18,20.