John Calvin on Numbers 27:5-7

5. And Moses brought their cause before the Lord. It is probable either that there was a difference of opinion, or that the minds of the judges were in doubt, as respecting an obscure and uncertain point. At any rate, it was expedient that the law should be laid down by God, lest any future controversy should arise; for, if a sentence had been pronounced by human judgment on the matter before them, the obstinacy of many would not perhaps have been sufficiently set at rest. It is worth while to remark the pious modesty of Moses, who was not ashamed to confess his ignorance, until he had been instructed by the mouth of God. Although he had promulgated the law forty years before, still he was always ready to learn. Besides, there is no doubt but that God impelled him to inquire of Himself, whenever any serious matters were in question, until his doctrine was absolutely perfect. And, although God does not now deliver from heaven what is to be done, nevertheless rulers are reminded that they ought to have recourse to God in points of perplexity, in order that He may instruct them by the Spirit of wisdom; and assuredly they will not be without this, if they ask Him; since he is no less ready to listen to them, than He here shewed Himself to be to Moses.