Genesis Rabbah 71:6
And when Rachel saw that she bore Jacob no children, Rachel envied her sister (Gen. 30:1). Rabbi Isaac observed: It is written, Let not your heart envy sinners (Prov. 23:17), yet you say, Rachel envied her sister! This, however, teaches that she envied her good deeds, reasoning: Were she not righteous, would she have borne children?
When I struggled with infertility, the jealousy of our barren matriarchs was a great comfort. Not only because their stories turned out well and they were blessed with their hearts' desire, but because their envy was exactly what I was feeling. Every time a girlfriend announced her pregnancy during those awful years, I was overcome with a jealousy I knew was wrong but could not help but feel.
Be it parenthood or a good job or the latest [fill-in-the-blank-of-your-heart's desire], it is difficult, in our material culture, not to want what others have. We know we shouldn't covet—that's one of the Ten Commandments, after all—but we can't control the way we feel.
Rabbi Isaac invites us to realign our values by sifting through our emotions for signals of priority. He wishes that we envied one another's deeds and good qualities, rather than possessions, children, or position in life. We cannot help the way we feel, but we can use our feelings as jumping-off points for inner work. Jealousy reveals a lack, not only of possessions (children, whatever), but of inner harmony. Rabbi Isaac is teaching us to use our jealousy as a focal point around which to work, so that we can end up in the place where that other famously jealous sibling, Esau, ended up when he says to his brother (Gen. 33:9): "I have enough."
If we learn to focus on what we each possess—an inner core of soul-heart—mind that is unique and holy-then we will be able to live with those feelings we cannot help, and turn them from stumbling blocks into stepping stones for emotional health and spiritual growth. We cannot help feeling jealous of our sisters sometimes, but we can help what we do with those feelings of jealousy. Using them as springboards from which to work toward inner harmony is one good bit of Jewish wisdom.