Can an ashkenazi man shave on Erev Shabbat that is also Rosh Chodesh? Whats the ikar hadin, chumra, heter etc? Thanks!

Shalom, Thank you for your question. Your question really two questions. The first is whether one may shave on Rosh Chodesh. The second is, may one shave on a Rosh Chodesh that falls out on Friday, erev Shabbat, in honor of Shabbat. The source for this question is found in the tzava’ah of Rabbi Yehudah Ha-Chasid (the will of Rabbi Yehudah) (1150-1217). This will comprises of 74 instructions, that include things not found in other sources, and without explanation. One of these is not to cut one’s hair, beard or nails on Rosh Chodesh. This is quoted by the Magen Avraham (260) and the Mishna Brurah (ibid 7). The language the Mishna Brurah uses is “There are places [where people] do not shave nor trim their nails on Rosh Chodesh, even if it falls out on Erev Shabbat, as it is written in the will of Rabbi Yehudah the Chasid”. In general, the obligation to follow what is written in will of Rabbi Yehudah Ha-Chasid is a matter of dispute. The Nodeh Yehudah rules that only that which is found in the Talmud is obligatory, and thus nearly all this “will” is not obligatory at all (Nodeh BeYehudah, Even HaEzer 79). Others hold that it only obligates his direct descendants. Whilst others still believe it does in fact obligate everyone (Shut Dvria Chaim, Even HaEzer 8). From the wording of the Mishna Brurah himself we can “hear” this argument, as, while he does quote this practice, he introduces it with the words “there are places where ...” indicating that not everyone follows this practice. In fact, the Mishna Brurah himself rules that during Seferat HaOmer, when we generally refrain from shaving, if Rosh Chodesh Iyar falls out on a Friday one may shave (493, 5). This would contradict the ruling of Rav Yehudah Ha Chasid. So, according to all opinions it is not forbidden by the Torah, or the Rabbis (DeOriatah or D’Rabanan) to shave on Rosh Chodesh. There certainly are people who follow the “will” of Rabbi Yehudah HaChasid, and would be very careful not to shave then – even if it fell out on Friday and they wanted to shave in honour of Shabbat. I have seen quoted that even those who are careful, if they were in a pressing situation (for example they forgot to shave on Thursday, and now would appear unseemly for Shabbat) that for a one time need they too could go ahead and shave. Those who do not have this custom (or who have no custom in relation to this issue) may continue to conduct themselves according to the words of the Rema in the Shulchan Aruch - “That if one needs to cut their hair (on Friday) it is a mitzvah to do so” [and presumably the same is true of shaving] (260, 1), and they need not be concerned with the words of Rabbi Yehudah HaChasid. Blessings.