Why does the Torah sometimes refer to Shabbat as a masculine noun and other times as a feminine noun?

Question

There are times when the Torah refers to Shabat in feminine as in Shmot (Ex.) 31:13 "...But you shall observe my Shabbats, for SHE is a sign". Other times the masculine voice is used as in Shmot (Ex.) 35:2 "...Anyone that does work on it" (Heb. _ "Bo", which is masculine).
Why does the Torah refer to Shabbat in both forms?

Answer 1

I had asked this question to a professor of Hebrew many years ago and he told me that the word שבת is female. The confusion arises because the Torah often refers to the day of שבת, which is male. Thus, 35:2 refers to the seventh day

שֵׁשֶׁת יָמִים תֵּעָשֶׂה מְלָאכָה וּבַיּוֹם הַשְּׁבִיעִי יִהְיֶה לָכֶם קֹדֶשׁ שַׁבַּת שַׁבָּתוֹן לַיהֹוָה כָּל הָעֹשֶׂה בוֹ מְלָאכָה יוּמָת

Sometimes it isn't so clear though, as in כל שומר שבת מחללו (Yeshayahu 56:2), which he had claimed was also a reference to the day, to יום השבת. An online search has revealed that in two separate Hebrew forums, simania and tapuz, this is the explanation given.

However, the Even-Shoshan Dictionary lists the noun as androgynous.

Answer 2

Much of the time in Tanakh, the masculine form is used in the context of Shabbat. This may be because the intent is to יום; (day).

However, there is another possibility for the verse in question (Exodus 31:13)

וְאַתָּ֞ה דַּבֵּ֨ר אֶל־בְּנֵ֤י יִשְׂרָאֵל֙ לֵאמֹ֔ר אַ֥ךְ אֶת־שַׁבְּתֹתַ֖י תִּשְׁמֹ֑רוּ כִּי֩ א֨וֹת הִ֜וא בֵּינִ֤י וּבֵֽינֵיכֶם֙ לְדֹרֹ֣תֵיכֶ֔ם לָדַ֕עַת כִּ֛י אֲנִ֥י יְקֹוָ֖ק מְקַדִּשְׁכֶֽם

Note that we are told to observe God's Sabbath's (plural) because it (singular) is a sign. (This anomaly is noted by the Alshikh and others).

One possible explanation is that observance (שמירה) of the Sabbath is the sign. שמירה is feminine.

However, there are similar verses which indicate that Shabbat itself is the sign:

וְשָׁמְר֥וּ בְנֵֽי־יִשְׂרָאֵ֖ל אֶת־הַשַּׁבָּ֑ת לַעֲשׂ֧וֹת אֶת־הַשַּׁבָּ֛ת לְדֹרֹתָ֖ם בְּרִ֥ית עוֹלָֽם: (יז) בֵּינִ֗י וּבֵין֙ בְּנֵ֣י יִשְׂרָאֵ֔ל א֥וֹת הִ֖וא לְעֹלָ֑ם

In which it is pretty clear that הוא (feminine given the niqqud) refers to the Sabbath, not its observance.

Additionally, there are other cases in which it is treated as feminine e.g. Exodus 31:14, and Leviticus 23:3.

Thus, one could either say that שנת is always feminine, and is only treated as masculine when the reference is to יום, or one could say that the noun is androgynous.

One argument in favor of the latter explanation is that Leviticus 23:3 mentions the word יום, net nevertheless retains the feminine usage.

פרשת אמור שֵׁ֣שֶׁת יָמִים֘ תֵּעָשֶׂ֣ה מְלָאכָה֒ וּבַיּ֣וֹם הַשְּׁבִיעִ֗י שַׁבַּ֤ת שַׁבָּתוֹן֙ מִקְרָא־קֹ֔דֶשׁ כָּל־מְלָאכָ֖ה לֹ֣א תַעֲשׂ֑וּ שַׁבָּ֥ת הִוא֙ לַֽיקֹוָ֔ק בְּכֹ֖ל מֽוֹשְׁבֹתֵיכֶֽם