Parshanut do Liczb 36:19

Before the leaders. Before Elozor is not written here, as in the case of the daughters of Tzelofchad, because they understood that such a thing could never be a permanent law, for it would cause the children of Israel to be divided from, and strangers to, each other. This could only take place with the agreement of the greatest men of the nation, or only in this generation until each man would take hold of his own inheritance. That is why they did not ask Elozor the kohein, for he wore the Urim and Tumim, about which is written Mishpat (Judgment). When consulting prophecy, the prophecy can be repealed. The decrees of the Urim and Thumimn, however, which are judgment, cannot be repealed; therefore they did not ask Elozor.