What did they used to do about putting on tefillin the day that witnesses could come and be mekadesh the new moon. If witnesses did come, and it was established R'H, then could they wear tefillin on R'H? If not, and witnesses didn't end up coming, and the next day would be R'H - what would happen to wearing tefillin the day before? Tosfos speaks about the korban mussaf and says it is a mitzvah d'rabbim - which doesn't seem like it wold apply to tefillin.
Thank you!
M Levy, Beachwood, OH, USA
The Biur Ha'Halachah (R' Chaim Kanievsky's "Biur Halachah" on Hilchos Kidush ha'Chodesh 3:6) discusses this matter at length, implying that there is an argument among the Rishonim regarding how they would treat this day. It would seem to me, especially based on his statement in Shekel ha'Kodesh (his "Mishnah Berurah" on Hilchos Kidush ha'Chodesh 5:7) that they would put on Tefilin, especially according to the opinion that they Davened a weekday Shacharis. Moreover, I would think that even the other opinion would say one could make a condition that if it does not turn out to be Yom Tov they are fulfilling the Mitzvah, and if it does turn out to be Yom Tov they are only intending to wear it "Derech Malbush." This is similar to the condition some make when saying Kriyas Shema without Berachos during the Zeman of the Magen Avraham as they are only going to say it with the Berachos during the Zeman of the Gra. (If the Halachah is like the Magen Avraham, I am fulfiling Kriyas Shema now. If not, I will fulfill it later when I say Kriyas Shema with the Berachos.)
All the best,
Yaakov Montrose