But if you have bitter envying and strife in your hearts, boast not, and lie not against the truth.
Read Chapter 3
George Leo Haydock
But if you have bitter zeal. He hints at that bitter, false zeal, which many teachers among the Jews, even after their conversion, were apt to retain against the converted Gentiles, pretending with lies, and against the truth of the Scriptures, that they are not to be made partakers of the blessings brought to all nations by the Messias.
Glory not, boast not in this pretended wisdom, which descendeth not from above, from God, but which is earthly, sensual, diabolical, from an evil spirit, which foments these jealousies and divisions; and where there are such emulations and divisions, there is nothing but inconstancy, and all kind of evils. (Witham)