"ZIMRI BEN SALU" (Numbers, the same place). For whoever discredits himself discredits his family along with him. Scripture is astonished over him: "ONE WHO BREACHES A FENCE" (Ecclesiastes 10:8). He is the son of one who made a fence — his ancestor. He was the first to be zealous against harlotry, as it is said: "AND THE TWO SONS OF JACOB, SIMEON AND LEVI, TOOK" (Genesis 34:25). Yet this one breached the fence that his ancestor had fenced.
Zimri Breaks the Fence His Ancestor Simeon Built
Midrash Tanchuma Buber, Pinchas 3:5
זמרי בן סלוא (במדבר שם). שכל מי שפוגם את עצמו פוגם את משפחתו עמו הכתוב תמיה עליו פור בן גודר אביו, קינא על הזנות תחלה, שנאמר ויקחו שני בני יעקב שמעון ולוי (בראשית לד כה), וזה פרץ גדר שגדר אביו.