מ. וּלְקַחְתֶּם לָכֶם בַּיּוֹם הָרִאשׁוֹן פְּרִי עֵץ הָדָר כַּפֹּת תְּמָרִים וַעֲנַף עֵץ עָבֹת וְעַרְבֵי נָחַל וּשְׂמַחְתֶּם לִפְנֵי יְ־הֹוָ־ה אֱלֹהֵיכֶם שִׁבְעַת יָמִים:
40. And you shall take for yourselves on the first day, the fruit of the Hadar tree, date palm fronds, a branch of a braided tree, and willows of the brook, and you shall rejoice before the Lord your God for a seven day period. (Vayikra 23:40)
This pasuk, in parshas Emor, contains the commandment for each Jewish Man to use his own Esrog on Succos – specifying ‘לָכֶם’, ‘for yourselves’.
. יט. וְעַתָּה כִּתְבוּ לָכֶם אֶת הַשִּׁירָה הַזֹּאת וְלַמְּדָהּ אֶת בְּנֵי יִשְׂרָאֵל שִׂימָהּ בְּפִיהֶם לְמַעַן תִּהְיֶה לִּי הַשִּׁירָה הַזֹּאת לְעֵד בִּבְנֵי יִשְׂרָאֵל
19: And now, write for yourselves this song, and teach it to the Children of Israel. Place it into their mouths, in order that this song will be for Me as a witness for the children of Israel. (Devarim 31:19)
This next pasuk, in Parshas Vayelech, commands every Jewish man to write a Sefer Torah using the same specification ‘לָכֶם’, ‘for yourselves’. However,the Halacha for the second usage of “לָכֶם” is not the same as the one for ‘פְּרִי עֵץ הָדָר’ – the Esrog. When performing the Mitzvah of writing a Sefer Torah, people can write them בשוטפות – in a group. A group of people share the writing of one Sefer Torah and each person is considered to have fulfilled their individual obligation to write a Sefer Torah.
How do we explain the difference between “לָכֶם” by the מצוה of esrog and “לָכֶם” by the מצוה of Sefer Torah? How do we justify the commonly accepted custom of sharing the great financial commitment of the writing of a Sefer Torah?
R Ahron Leib Shteinman explains in reference to the מצוה of esrog: “לָכֶם” (in Gemara Succos 35a) is used to teach that financial ownership (בעלת ממון) of an esrog is not enough to fulfil the mitzva. There needs to be the possibility of extracting maximum productivity ie a היתר אכילה – the ability to eat it and use it up (destroy it). With shared ownership, a partner has the right to use the asset, but not deplete or destroy it; as this would deprive the co-owners of their rights. , In this case they require recompense. So in the case of the Esrog, if it cannot be used to the fullest extent ie eating it,then there is a deficiency in “לָכֶם” Thus it is clear that since a jointly owned esrog cannot be fully used by an individual partner, one cannot perform the mitzva with it.
However, with the mitzvah of Sefer Torah, the fullest use of the shared item consists of reading it and learning from it. This does not depreciate the asset nor detract from another owner’s share at all. If one partner were to read and learn from it, he is certainly using it to its fullest extent, so there is no deficiency in “לָכֶם”, and all of the participants can fulfill their full obligation even with only a partial share. Indeed, all can use it together to the same extent as it is used individually – so the “לָכֶם” aspect is equal both individually and collectively.
This then answers both our questions, showing that many people can share equally in the great Mitzvah of writing a Sefer Torah but each man must purchase his own individual esrog.