Adam Clarke Bible Commentary
Let my wife grind unto another - Let her work at the handmill, grinding corn; which was the severe work of the meanest slave. In this sense the passage is understood both by the Syriac and Arabic. See Exo 11:5 (note), and Isa 47:2 (note); and see at the end of the chapter, Isa 31:8 (note).
And let others bow down upon her - Let her be in such a state as to have no command of her own person; her owner disposing of her person as he pleases. In Asiatic countries slaves were considered so absolutely the property of their owners, that they not only served themselves of them in the way of scortation and concubinage, but they were accustomed to accommodate their guests with them! Job is so conscious of his own innocence, that he is willing it should be put to the utmost proof; and if found guilty, that he may be exposed to the most distressing and humiliating punishment; even to that of being deprived of his goods, bereaved of his children, his wife made a slave, and subjected to all indignities in that state.
John Gill Bible Commentary
For this is an heinous crime,.... Adultery; it is contrary to the light of nature, and is condemned by it as a great sin, Gen 20:9; as well as contrary to the express will and law of God, Exo 20:14; and, though all sin is a transgression of the law of God, and deserving of death; yet there are some sins greater and more heinous than others, being attended with aggravating circumstances; and such is this sin, it is a breach of the marriage contract and covenant between man and wife; it is doing injury to a man's property, and to that which is the nearest and dearest to him, and is what introduces confusion into families, kingdoms, and states; and therefore it follows:
yea, it is an iniquity to he punished by the judges; who might take cognizance of it, examine into it, and pass sentence for it, and execute it; and, if they neglect do their duty, God, the Judge of all the earth, will punish for it in the world to come, unless repented of: "for whoremongers and adulterers God will judge", Heb 13:4; the punishment of adultery was death by the law of God, and that by stoning, as appears from Lev 20:10; and it is remarkable, that the Heathens, who were ignorant of this law, enjoined the same punishment for it; so Homer (e) introduces Hector reproving Paris for this sin, and suggests to him, that if he had his deserved punishment, he would have been clothed with a "stone coat", as he beautifully expresses it; which Suidas (f) explains, by being overwhelmed with stones, or stoned; as Eustathius (g).
(e) Iliad. 3. v. 57. (f) In voce (g) In Homer. ibid.