Rashi on Numbers 30:15/רש"י על במדבר ל׳:ט״ו

1מיום אל יום [BUT IF HER HUSBAND ALTOGETHER HOLD HIS PEACE AT HER] FROM DAY TO DAY — In order that you should not say that ביום שמעו in v. 13 means that the husband has the right of annulling from the time on the day when she made the vow to the same time on the next day (i.e., twenty-four hours), it accordingly states מיום אל יום, i.e., from the day when she makes the vow up to the next day, — to tell you that he may annul the vow only up to when it becomes dark, [for then another day begins] (cf. Nedarim 76b).