Musar zu Ijow 9:39

When Moses, the man described as the most humble man who ever lived, permitted himself to say: "Any matter which is too difficult for you bring to me," G–d reacted by proving that he could not even deal with a problem that women knew the answer to, i.e. the problem presented by the daughters of Tzlofchod (Deut. 1,17, concerning Numbers 27,4-5).