We are told that we are not to desire that which belongs to another. Obsessing over another person’s property will only lead to scheming with the intent of depriving him of it. This mitzvah is related to, but different from, the prohibition against coveting in the “Ten Commandments” (Mitzvah #38). Coveting actually involves the plot to acquire another’s property against, but this mitzvah addresses the urge that precedes it.
The obvious question is how we can be commanded not to desire something. After all, isn’t such a thing beyond a person’s control? The reality is that we can learn to master our urges. Saying that such desires are beyond our control is mere justification. God knows our innermost thoughts, so He is well aware whether or not a person made the attempt to rise above his baser urges.
The reason for this mitzvah is what we said about coveting: a desire for someone else’s lot is a tacit criticism of God in that a person is not satisfied with what He has given him. A person should accept God’s judgment that person A should have such-and-such while person B should have something else.
This mitzvah applies to both men and women in all times and places. In the Talmud, it is discussed in tractate Baba Metzia on page 5b. This mitzvah is codified in the Shulchan Aruch in Choshen Mishpat 359. It is #266 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos and #41 of the 194 negative mitzvos that can be observed today in the Chofetz Chaim’s Sefer HaMitzvos HaKatzar.