Midrasch zu Wajikra 23:3

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.