John T. Carroll, The Return of Jesus in Early Christianity (Peabody, MA: Hendrickson Publishers, 2000), 125:
Arrogance and envy, according to James, keep company with wealth. Indictment of the rich, and of those who show partiality to them, is a major theme of the letter (1:9-11; 2:1-7; 5:1-6). With the help of Isa 40:6-7, James observes that the wealthy have no more permanence than grass (1:10-11; cf. “mist” in 4:14). It is no accident that the concrete illustrations of “doing the law” or of “good works” involve compassionate response to persons afflicted by poverty and need (e.g., 1:27; 2:8-17). The rich, by contrast, not only show contempt for and neglect the poor but also exploit and oppress them (2:6; 5:4-6). If the social world inhabited by readers of James shows partiality to the wealthy, God favors the poor, who will be heirs of the divine realm (2:5).
The Amateur Exegete 