John Gill Bible Commentary

So shall not the inheritance of the children of Israel remove from tribe to tribe,.... Which shows that this concerns all the tribes of Israel, though yet not fully expressed, as it is afterwards: for everyone of the children of Israel shall keep himself to the inheritance of the tribe of his fathers; or cleave (a) to a wife in that tribe for marriage; this word is used in the original institution of it, Gen 2:24 though they were not strictly obliged to marry in their own tribe; and frequently they did intermarry with other tribes, which, had it been unlawful, would not have been done, as it was by kings, and priests, and others; nor was there any danger of an inheritance going into another tribe by a man's marrying into it; wherefore this signifies only, that they were to be careful to keep their inheritances in their tribe; and therefore if any of them had no sons, only daughters, he was to marry them in his own tribe and family, that the inheritance might not remove, as follows(a) "adhaerebunt", Montanus, Vatablus, Junius & Tremellius.