Rashi on Leviticus 23:4/רש"י על ויקרא כ״ג:ד׳

1'אלה מועדי ה THESE ARE THE APPOINTED FESTIVALS OF THE LORD [EVEN CONVOCATIONS OF HOLINESS WHICH YE SHALL PROCLAIM] — Above (v. 2), where similar words are used, Scripture is speaking of proclaiming the year to be a leap-year, here it is speaking of the קדוש החדש, sanctification of the month (a technical expression denoting proclaiming when is the New Moon — the beginning of a month) (Sifra, Emor, Chapter 10 1).