Sifra 11.0.19

Emor, Chapter 10

1) Above (Vayikra 23:2), intercalation of the year is being spoken of, and here (Vayikra 22:4) sanctification of the month is being spoken of. If (the moon) were seen clearly, or witnesses came and testified (to that effect) before them (beth-din), and they were unable to proclaim "It is intercalated until it became dark — whence is it derived that it is intercalated? From "which you shall call (them) in their times." If you called them, they are My festivals. If not, they are not My festivals.

2) If they sanctified it (erroneously) without witnesses, or if witnesses came and testified and were found to be scheming witnesses, whence is it derived that it is sanctified? From which you shall call (them) in their times." If you called them, they are My festivals. If not, they are not My festivals.

3) If they sanctified it perforce or unwittingly or mistakenly, whence is it derived that it is (nevertheless) sanctified? From which you shall call (them) in their times. "them" — even mistakenly; them — even perforce.

4) If they sanctified it before its time or one day after its intercalation, I might think that it were sanctified; it is, therefore, written "these are the festivals." And not those.

5) I might think that just as they intercalate the year and the month to answer some special need, so they can sanctify the month to answer some special need. It is, therefore, written (Shemoth 12:2) "This month is for you" — the month is to be followed.

6) I might think that if two days were needed (for intercalation of the month instead of one), they could be added; it is, therefore, written (Vayikra 23:6) ("And on the fifteenth) day of this month (is the festival of matzoth") — only one day can be added. And whence is it derived that the Sabbath may be desecrated (by the messengers to come to beth-din and) to testify about them? From "These are the festivals of the L–rd (which you shall call in their [proper] times.")

7) I might think that just as the Sabbath may be desecrated to testify about it (the moon), so, it may be desecrated to apprise (the exiles of it) so that they can observe (the festivals on their proper times); it is, therefore, written "which you shall call" — You may desecrate the Sabbath for calling (i.e., sanctifying) it, but not for apprising (the exiles of it).