Job 15:2

“Should a wise man utter vain knowledge, etc.] As Job had been thought to be, or as he himself thought he was, which he might say sarcastically; or as he really was, not worldly wise, nor merely wise in things natural, but in things divine; being one that had the fear of God, which is the beginning of wisdom, and wisdom itself; believed in Christ, and walked wisely and circumspectly before men; now it is not becoming such a man to utter vain knowledge, or such knowledge as is like the wind, or, as the Targum, windy knowledge; empty, not solid, nor satisfying, but swells and puffs up, and is knowledge falsely so called; but it does not appear that Job did utter such vain and fruitless things…”

“Should a wise man - Referring to Job, and to his claims to be esteemed wise; see Job 12:3; Job 13:2, Job 13:6. The argument of Eliphaz here is, that the sentiments which Job had advanced were a sufficient refutation of his pretensions to wisdom. A wise man would not be guilty of “mere talk,” or of using language that conveyed no ideas. Utter - literally, answer. It refers to the replies which Job had made to the arguments of his friends. Vain knowledge - Margin, “Knowledge of wind.” So the Hebrew; see Job 6:26; Job 7:7. The “wind” is used to denote what is unsubstantial, vain, changing. Here it is used as an emblem of remarks which were vain, empty, and irrelevant. And fill his belly - Fill…”

“Fill - Satisfy his mind and conscience. East wind - With discourses not only unprofitable, but also pernicious both to himself and others; as the east - wind was in those parts. Job 15:4”

“15:2-3 You are nothing but a windbag (literally You fill your belly with the east wind): Since the east wind was hot, it might represent heated (Exod 14:21; Hos 13:15; Jon 4:8) or violent (Job 27:21; Jer 18:17) speech.”

“a wise man: Job 11:2, Job 11:3, Job 13:2; Jam 3:13 vain knowledge: Heb. knowledge of wind, Job 6:26, Job 8:2 fill: Hos 12:1 Job 15:3”