Or HaChaim on Numbers 36:9/אור החיים על במדבר ל״ו:ט׳

1 ולא תסב נחלה, "so that an inheritance not move (from one tribe to another), etc. The reason the Torah repeats this both negatively and positively is as I have explained already that it was only well meant advice not legislation. The Torah therefore had to repeat that in all instances other than the daughters of Tzelofchod this was a matter of legislation.