Numbers 36:8,9

And every daughter, that possesseth an inheritance... — The particular direction which was given in the case of the daughters of Zelophehad is extended in these verses into a general and permanent law that no heiress in Israel should marry out of her father’s tribe, in order that the inheritance might not be transferred from one tribe to another, and thus, in process of time, the division of the land amongst the tribes, which was made under Divine direction, be materially changed.