The head of the beis din says, “It is sanctified!”  And all the people respond after him, “It is sanctified! It is sanctified!”  Whether it appeared at its [expected] time or whether it did not appear at its [expected] time, they sanctify [the day].  R’ Elazar bar Tzadok says: If it did not appear at its [expected] time, they do not sanctify, for it has already been sanctified by Heaven.