“Therefore, the Jewish people will not eat the gid hanasheh, sciatic nerve, that is on the hip joint, to this day” (Breisheet 32:33). Sefer Breisheet provides much information on how not to act; we read about every kind of social dysfunction—be it drinking, sibling rivalry, jealousy, greed or more violent crimes such as robbery, kidnapping, rape, incest and murder.
It is for good reason that co-wives are described as tzarot, literally, problems. Competing as they inevitably must for the same man, their relationship is destined to be one of jealousy, bickering and even hatred. Jewish law, recognizing this sad situation, disqualifies the testimony of one of the tzarot regarding the other—we are afraid that they will simply lie.