The Alter Rebbe discusses the enduring benefit that the living can provide to souls through Torah, mitzvot, and prayer, especially in relation to the deceased. This provides a Hasidic framework for memorial actions even long after death.
אֲבָל לְאַחַר פְּטִירָתוֹ, לְפִי שֶׁמִּתְפָּרְדִים בְּחִינַת הַנֶּפֶשׁ שֶׁנִּשְׁאֲרָה בַּקֶּבֶר מִבְּחִינַת הָרוּחַ שֶׁבְּגַן עֵדֶן, שֶׁהֵן שָׁלֹשׁ מִדּוֹת הַלָּלוּ, לְפִיכָךְ יָכוֹל כָּל הַקָּרוֹב אֵלָיו לְקַבֵּל חֵלֶק מִבְּחִינַת רוּחוֹ שֶׁבְּגַן עֵדֶן, הוֹאִיל וְאֵינָהּ בְּתוֹךְ כְּלִי וְלֹא בִּבְחִינַת מָקוֹם גַּשְׁמִי, כַּנּוֹדָע מַאֲמַר רַבּוֹתֵינוּ־זִכְרוֹנָם־לִבְרָכָה עַל יַעֲקֹב אָבִינוּ עָלָיו־הַשָּׁלוֹם שֶׁנִּכְנַס עִמּוֹ גַּן עֵדֶן, וְכֵן כָּתַב בְּסֵפֶר עֲשָׂרָה מַאֲמָרוֹת, שֶׁאֲוִיר גַּן עֵדֶן מִתְפַּשֵּׁט סָבִיב כָּל אָדָם, וְנִרְשָׁמִים בַּאֲוִיר זֶה כָּל מַחְשְׁבוֹתָיו וְדִבּוּרָיו הַטּוֹבִים בַּתּוֹרָה וַעֲבוֹדַת ה׳ (וְכֵן לְהֵיפֶךְ חַס וְשָׁלוֹם נִרְשָׁמִים בַּאֲוִיר הַמִּתְפַּשֵּׁט מִגֵּיהִנֹּם סָבִיב כָּל אָדָם). וְנוֹדָע, שֶׁכָּל דָּבָר שֶׁבִּקְדוּשָּׁה אֵינוֹ נֶעְקָר לְגַמְרֵי מִכֹּל וָכֹל מִמְּקוֹמוֹ וּמַדְרֵגָתוֹ הָרִאשׁוֹנָה, גַּם לְאַחַר שֶׁנִּתְעַלָּה לְמַעְלָה לְמַעְלָה. וּבְחִינָה זוֹ הָרִאשׁוֹנָה שֶׁנִּשְׁאֲרָה לְמַטָּה בְּגַן עֵדֶן הַתַּחְתּוֹן בִּמְקוֹמוֹ וּמַדְרֵגָתוֹ הָרִאשׁוֹנָה, הִיא הַמִּתְפַּשֶּׁטֶת בְּתַלְמִידָיו, כָּל אֶחָד כְּפִי בְּחִינַת הִתְקַשְּׁרוּתוֹ וְקִרְבָתוֹ אֵלָיו בְּחַיָּיו וּבְמוֹתוֹ בְּאַהֲבָה רַבָּה, כִּי, הַמְשָׁכַת כָּל רוּחָנִיּוּת, אֵינָהּ אֶלָּא עַל־יְדֵי אַהֲבָה רַבָּה, כְּמוֹ שֶׁכָּתוּב בַּזּוֹהַר הַקָּדוֹשׁ דְּרוּחַ דִּרְעוּתָא דְלִבָּא אַמְשִׁיךְ רוּחַ מִלְּעֵילָא, רַק אִם יִכּוֹן לִקְרַאת אֱלֹהָיו בַּהֲכָנָה רַבָּה וִיגִיעָה עֲצוּמָה, לְקַבֵּל שָׁלֹשׁ מִדּוֹת הַלָּלוּ, כְּדֶרֶךְ שֶׁהוֹרָהוּ רַבּוֹ, וּכְמַאֲמַר רַבּוֹתֵינוּ־זִכְרוֹנָם־לִבְרָכָה: ״יָגַעְתָּ וּמָצָאתָ – תַּאֲמִין״.
But after his passing, because the nefesh [which remains in the grave] is separated from the ruach [i.e., these three attributes] which is in the Garden of Eden, whoever is close to him can receive a part from the aspect of his ruach [which is in the Garden of Eden], because it is no (longer) within a vessel, nor on the plane of physical space. Thus is known the saying of our Sages, of blessed memory, with reference to our father Jacob, peace be to him, that “the Garden of Eden entered with him.” Likewise it is stated in the book Asarah Maamarot that the sphere of the Garden of Eden spreads itself around every person, and in this sphere are recorded all his good thoughts and utterings of Torah and Divine service (and likewise to the contrary, Heaven forfend: they are recorded in the sphere of Gehinom, which spreads itself around every person). Now it is known that something sacred is never wholly and totally uprooted from its place and original level, even after it has reached the highest point. Thus it is this original aspect, remaining below, in the Lower Garden of Eden, in its place and original level, which extends itself among his disciples, each one according to the level of his alliance and closeness to (the tzaddik) during his lifetime and after his death out of a magnanimous love. For the efflux of anything spiritual is but by means of a magnanimous love. Thus it is stated in the sacred Zohar that the spirit (ruach) in a mode of the willingness of the heart (reuta deliba) elicits a spirit from above; thus only when he will prepare himself toward his G–d with a great preparation and immense effort to receive these attributes in the way that his master taught him, and as the saying of our Sages, of blessed memory: “If you have labored and (claim to have) found—believe it.”