Another interpretation of "For I give you a good doctrine" (Proverbs 4:2): A person who borrows from others, buys merchandise, and sets out on the road sometimes loses everything. But the Torah is not like that. Rather, a person studies one chapter here and one chapter there, and he is sustained by them. Thus, "For I give you a good doctrine." The Holy One, blessed be He, said to them: "The Torah was Mine, and you took it. Take Me along with it." This is what is written, "And let them take a portion (terumah) for Me" (Exodus 25:2). Resh Lakish said: Thus did our masters teach. Five may not set apart terumah, and if they did set it apart, their terumah is not valid: the deaf-mute, the imbecile, the minor, one who sets apart from what is not his, and a non-Jew who set apart from what belongs to a Jew. Their terumah is not terumah. And all of these are derived from this very verse. "Speak to the children of Israel" (Exodus 25:2): this excludes the deaf-mute, who neither hears nor speaks. "Whose heart moves him": this excludes the imbecile, whose heart does not move him to generosity. "From every man": this excludes the minor, who is not yet a man. And one who sets apart from what is not his, as it is said "from every man" [meaning] from what is theirs. And a non-Jew who set apart from what belongs to a Jew, even with his permission, as it is said "Speak to the children of Israel": this excludes a non-Jew, who is not of Israel.
Torah as Good Merchandise and the Five Whose Terumah Is Void
Yalkut Shimoni on Torah 363:6
דָּבָר אַחֵר "כִּי לֶקַח טוֹב". אָדָם שֶׁהוּא לֹוֶה מִבְּנֵי אָדָם וְלוֹקֵחַ סְחוֹרָה וְיוֹצֵא לַדֶּרֶךְ פְּעָמִים שֶׁהִיא מַפְסֶדֶת, אֲבָל הַתּוֹרָה אֵינָהּ כֵן, אֶלָּא לוֹמֵד אָדָם מִכָּאן פֶּרֶק אֶחָד מִכָּאן פֶּרֶק אֶחָד, הוּא מִתְפַּרְנֵס בָּהֶן, הֲוֵי "כִּי לֶקַח טוֹב". אָמַר לָהֶם הַקָּדוֹשׁ בָּרוּךְ הוּא הַתּוֹרָה הָיְתָה שֶׁלִּי וּלְקַחְתֶּם אוֹתָהּ, קְחוּ אוֹתִי עִמָּהּ. הָדָא הוּא דִּכְתִיב, וְיִקְחוּ לִי תְּרוּמָה. אָמַר רֵישׁ לָקִישׁ, כָּךְ שָׁנוּ רַבּוֹתֵינוּ חֲמִשָּׁה לֹא יִתְרֹמוּ וְאִם תָּרְמוּ אֵין תְּרוּמָתָן תְּרוּמָה, הַחֵרֵשׁ, שׁוֹטֶה וְקָטָן וְהַתּוֹרֵם אֶת שֶׁאֵינוֹ שֶׁלּוֹ וְנָכְרִי שֶׁתָּרַם אֶת שֶׁל יִשְׂרָאֵל, אֵין תְּרוּמָתָן תְּרוּמָה, וְכֻלָּן מִן הַפָּסוּק הַזֶּה דַּבֵּר אֶל בְּנֵי יִשְׂרָאֵל יָצָא חֵרֵשׁ שֶׁאֵינוֹ שׁוֹמֵעַ וְאֵינוֹ מְדַבֵּר, אֲשֶׁר יִדְּבֶנּוּ לִבּוֹ יָצָא שׁוֹטֶה שֶׁאֵין לִבּוֹ נוֹדְבוֹ, מֵאֵת כָּל אִישׁ יָצָא קָטָן שֶׁאֵינוֹ אִישׁ וְהַתּוֹרֵם אֶת שֶׁאֵינוֹ שֶׁלּוֹ שֶׁנֶּאֱמַר מֵאֵת כָּל אִישׁ מִשֶּׁלָּהֶן, וְנָכְרִי שֶׁתָּרַם אֶת שֶׁל יִשְׂרָאֵל אֲפִלּוּ בִּרְשׁוּתוֹ שֶׁנֶּאֱמַר דַּבֵּר אֶל בְּנֵי יִשְׂרָאֵל יָצָא נָכְרִי שֶׁאֵינוֹ מִיִּשְׂרָאֵל.