Matthew Poole and continuators on Job 6:5

5. Doth the wild Ass bray when he hath grass? or loweth the Ox over his fodder ?

Thou wonderest that my disposition and carriage is so greatly altered from what it was, Ch. 4. 3. 4, 5. but thou mayest easily learn the reason of it from the brute Beasts, the Ass and Ox, who when they have convenient and common food, are quiet and contented; but when they want that, they will resent it, and complain in their way by braying or lowing: See Ier. 14. 6. And therefore my carriage is agreeable to those common principles of nature which are both in Men and Beasts, by which their disposition and deportment is generally suitable to their condition. It is no wonder that you complain not who live in ease and prosperity, nor did I, when it was so with me; but if you felt what I feel, you would be as full of complaints, as I am.

Marginal references: Heb. at grass.