Eruvin 96B

כרבי יוסי, דאמר: נשים סומכות רשות.

in accordance with the opinion of R' Yosei, who said: It is optional for women to place their hands on the head of a sacrificial animal before it is slaughtered. Although only men have this obligation, women may perform that rite if they wish. Similarly, women may perform other mitzvot that they have no obligation to fulfill.

דאי לא תימא הכי, אשתו של יונה היתה עולה לרגל ולא מיחו בה, מי איכא למאן דאמר רגל לאו מצות עשה שהזמן גרמא הוא? אלא קסבר רשות, הכא נמי רשות.

As, if you do not say so, that this tanna holds in accordance with the opinion of R' Yosei, the baraita states that Jonah’s wife would ascend to Jerusalem for the Festival pilgrimage and the rabbis did not reprimand her. Is there anyone who says that the mitzva of Festival pilgrimage is not a time-bound positive mitzva and that women are obligated to fulfill it? Rather, he holds that she did not embark on the pilgrimage as an obligation, but that it was optional; here, too, with regard to tefillin, it is optional. Consequently, no proof can be cited from this baraita as to whether or not Shabbat is a fit time for tefillin.

אלא האי תנא היא דתניא: המוצא תפילין, מכניסן זוג זוג. אחד האיש ואחד האשה, אחד חדשות ואחד ישנות, דברי רבי מאיר. רבי יהודה אוסר בחדשות, ומתיר בישנות.

Rather, who is the tanna who maintains that Shabbat is a time for tefillin? It is this tanna who taught the halakha, as it was taught in the Tosefta: One who finds tefillin brings them in pair by pair, whether the finder is a man or whether she is a woman, and whether the tefillin are new or whether they are old. This is the statement of R' Meir. R' Yehuda prohibits bringing in new tefillin since they might merely be amulets in the form of tefillin, but he permits bringing in old ones, which are certainly valid tefillin.