למשפחות מנשה בן יוסף. האריך הכתוב ליחס הבנות האלה עד יוסף לפי שהוא חיבב את הארץ, שנאמר (שמות יג) והעליתם את עצמותי, וגם בנותיו מחבבות את הארץ. וללמדך שכלן כשרים, שכל מי שמעשיו ומעשה אבותיו סתומין ופרט לך הכתוב באחד מהם ליחסו לשבח הוא צדיק בן צדיק, ואם מיחסו לגנאי, כענין שכתוב (מלכים ב כה) בא ישמעאל בן נתניה בן אלישמע מזרע המלוכה, בידוע שכל הנזכרים עמו היו רשעים.
למשפחות מנשה בן יוסף, “of the family of Menashe, son of Joseph.” The reason the Torah went out of its way to trace the ancestry of these girls all the way back to Joseph was their fondness of the land of Israel, a fondness which had also characterized their ancestor Joseph who had commanded his surviving brothers to take his remains with them to the Holy Land when the time of the redemption from Egypt would arrive (Genesis 50,28).
Furthermore, this teaches that all the ancestors of the daughters of Tzelofchod were righteous seeing that we have a rule that when the Bible mentions a person to his credit and it mentions his ancestors without reporting anything specific about the deeds of his or her ancestors, both he and his ancestors may be presumed to have been righteous, i.e. a צדיק בן צדיק. If, on the other hand, that person is singled out because of something improper he had done and the Torah also mentions the names of his ancestors without describing them as meritorious, it is clear that not only he but also these ancestors were wicked. The classic example is found in Kings II 25,25: “Yishmael, son of Natanya son of Elishama of royal descent came with ten men and murdered Gedalyah.” You may be certain that not only this Yishmael but also all the forebears of his who are listed were wicked people.