If a person accepted Shabbos early and then remembered that he didn’t put on tefillin that day, and it’s still before shkia, what should he do?
Also, if he accepted Shabbos early but now has the opportunity to put tefillin on another Jew for whom it’s still Friday (and that person cannot do it by himself), is this OK?
This is an interesting question. I think that under the circumstances, it will be permitted to put on the Tefillin, but this should be done without a Beracha.
The prohibition of putting on Tefillin on Shabbos is because Tefillin are an “os,” and there is no need for them on Shabbos since Shabbos itself is an “os.”
This implies that the prohibition is rabbinic, and related to a “zilzul” in the honor of Shabbos.
Therefore, there are two reasons why it will be permitted to put on Tefillin after accepting Shabbos:
1. Because after a private acceptance of Shabbos it remains permitted to perform rabbinic melachos.
2. Because there is no “zilzul” in the honor of Shabbos in putting on Tefillin at this time, which is not yet Shabbos for the entire world, and only a “personal” Shabbos for the person in question.
Although the Mishnah Berurah mentions a concern for “bal tosif,” this won’t apply when one is performing the Friday mitzvah of putting on Tefillin.
However, based on the Shulchan Aruch (30:5) and Mishnah Berurah (17), one should put on Tefillin at this time without a berachah, as we find for somebody who davened Maariv early during the week.
The idea will apply all the more to putting on Tefillin for somebody else.