Question
What do the Jewish sources tell us about the mother-in-law/daughter-in-law relationship?
Answer
The Book of Ruth tells about a daughter-in-law who refused to leave her mother-in-law after her husband died, and who was rewarded by finding a new husband and becoming the great-grandmother of King David. Unfortunately, there is often tension between in-laws, leading to animosity, rivalry, or lack of impartiality; see Mishnah Yevamos 15:4.