Halacha

הלכה א
הָעַכּוּ''ם וְגֵר תּוֹשָׁב לוִֹין מֵהֶן וּמַלְוִין אוֹתָן בְּרִבִּית שֶׁנֶּאֱמַר (דברים כג כ) "לֹא תַשִּׁיךְ לְאָחִיךָ" לְאָחִיךְ אָסוּר וְלִשְׁאָר הָעוֹלָם מֻתָּר. וּמִצְוַת עֲשֵׂה לְהַשִּׁיךְ לְעַכּוּ''ם שֶׁנֶּאֱמַר (דברים כג כא) "לַנָּכְרִי תַשִּׁיךְ" מִפִּי הַשְּׁמוּעָה לָמְדוּ שֶׁזּוֹ מִצְוַת עֲשֵׂה וְזֶהוּ דִּין תּוֹרָה:
כסף משנה
1.
One may lend money to and borrow money from a gentile and a resident alien at interest, as implied by Deuteronomy 23:20: "Do not offer interest to your brother." We may infer: Offering - and taking - interest from "your brother" is prohibited; from people at large, by contrast, it is permitted.
It is a positive mitzvah to lend money to a gentile at interest, as Ibid:21 states: "You may offer interest to a gentile." The Oral Tradition teaches that this is a positive commandment. This is the Scriptural Law.

הלכה ב
אָסְרוּ חֲכָמִים שֶׁיִּהְיֶה יִשְׂרָאֵל מַלְוֶה אֶת הָעַכּוּ''ם בְּרִבִּית קְצוּצָה אֶלָּא בִּכְדֵי חַיָּיו. גָּזְרוּ שֶׁמָּא יִלְמֹד מִמַּעֲשָׂיו בְּרֹב יְשִׁיבָתוֹ עִמּוֹ. לְפִיכָךְ מֻתָּר לִלְווֹת מִן הָעַכּוּ''ם בְּרִבִּית שֶׁהֲרֵי הוּא בּוֹרֵחַ מִלְּפָנָיו וְאֵינוֹ רָגִיל אֶצְלוֹ. וְתַלְמִיד חָכָם שֶׁאֵינוֹ רָגִיל בּוֹ לִלְמֹד מִמַּעֲשָׂיו מֻתָּר לְהַלְווֹת לָעַכּוּ''ם בְּרִבִּית אֲפִלּוּ לְהַרְוִיחַ. וְכָל אֲבַק רִבִּית עִם הָעַכּוּ''ם מֻתֶּרֶת לַכּל:
כסף משנה
2.
Our Sages, however, forbade a Jew from lending money to a gentile at a fixed rate of interest beyond what is necessary for him to earn his livelihood. They enacted this decree lest the lender learn from the gentile's deeds as a result of the large extent of his contact with him. Therefore even according to the Sages, it is permitted to borrow money from a gentile at interest, for the Jew will flee from him, and will not frequent his company.
Torah scholars will not learn from a gentile's conduct. Hence, it is permitted for them to lend money to a gentile at interest, even to make a profit. Any transactions in the category of "the shade of interest" that involve gentiles are permitted for everyone.

הלכה ג
יִשְׂרָאֵל שֶׁלָּוָה מָעוֹת מִן הָעַכּוּ''ם בְּרִבִּית וּבִקֵּשׁ לְהַחְזִירָם לוֹ. מְצָאוֹ יִשְׂרָאֵל אַחֵר וְאָמַר לוֹ תְּנֵם לִי וַאֲנִי מַעֲלֶה לְךָ כְּדֶרֶךְ שֶׁאַתָּה מַעֲלֶה לָעַכּוּ''ם. הֲרֵי זוֹ רִבִּית קְצוּצָה אֲפִלּוּ הֶעֱמִידוֹ אֵצֶל הָעַכּוּ''ם עַד שֶׁיִּטּל הָעַכּוּ''ם מְעוֹתָיו וְיַחְזֹר וְיִתְּנֵם בְּיַד יִשְׂרָאֵל הָאַחֵר:
כסף משנה
3.
The following law applies when a Jew borrowed money from a gentile at interest, and when he seeks to return it to him another Jew meets him and tells him: "Give it to me and I will pay you the rate of interest that you pay the gentile." This is forbidden, even if the original borrower brings the other Jew to the gentile. Instead, the gentile must take back his money and then give it as a loan to the other Jew.

הלכה ד
עַכּוּ''ם שֶׁלָּוָה מָעוֹת מִיִּשְׂרָאֵל בְּרִבִּית וּבִקֵּשׁ לְהַחְזִירָם לוֹ. מְצָאוֹ יִשְׂרָאֵל אַחֵר וְאָמַר לוֹ תְּנֵם לִי וַאֲנִי מַעֲלֶה לְךָ כְּדֶרֶךְ שֶׁאַתָּה מַעֲלֶה לְיִשְׂרָאֵל הֲרֵי זֶה מֻתָּר. וְאִם הֶעֱמִידוֹ אֵצֶל יִשְׂרָאֵל אַף עַל פִּי שֶׁנָּתַן הָעַכּוּ''ם הַמָּעוֹת בְּיָדוֹ הוֹאִיל וּמִדַּעַת יִשְׂרָאֵל נָתַן הֲרֵי זוֹ רִבִּית קְצוּצָה:
כסף משנה
4.
When, by contrast, a gentile borrows money from a Jew at interest and desires to return it to him, and another Jew meets the gentile and tells him: "Give it to me and I will pay you the rate of interest that you pay the other Jew," this is permitted. If, however, the gentile brought the Jewish borrower to the Jewish lender and informed him of the loan, this is considered fixed interest, for he gave the money with the knowledge of the Jewish lender. This applies even if the gentile gave the Jewish borrower the money.

הלכה ה
אָסוּר לְיִשְׂרָאֵל לִתְלוֹת מְעוֹתָיו בְּיַד עַכּוּ''ם כְּדֵי לְהַלְווֹתָן בְּרִבִּית לְיִשְׂרָאֵל. וְעַכּוּ''ם שֶׁהִלְוָה אֶת יִשְׂרָאֵל בְּרִבִּית אָסוּר לְיִשְׂרָאֵל אַחֵר לִהְיוֹת לוֹ עָרֵב שֶׁכֵּיוָן שֶׁבְּדִינֵיהֶם שֶׁתּוֹבֵעַ הֶעָרֵב תְּחִלָּה נִמְצָא הֶעָרֵב תּוֹבֵעַ אֶת יִשְׂרָאֵל בְּרִבִּית שֶׁהֶעָרֵב חַיָּב בָּהּ לָעַכּוּ''ם. לְפִיכָךְ אִם קִבֵּל עָלָיו הָעַכּוּ''ם שֶׁלֹּא יִתְבַּע אֶת הֶעָרֵב תְּחִלָּה הֲרֵי זֶה מֻתָּר:
כסף משנה
5.
It is forbidden for a Jew to entrust his money to a gentile so that he can lend them to a Jew at interest.
When a gentile loans money to a Jew at interest, it is forbidden for another Jew to serve as a guarantor. The rationale is that according to their laws, the lender may demand payment from the guarantor first. Thus, after paying the debt, the guarantor will demand payment for the interest that he is obligated to the gentile. Hence, if the gentile makes a commitment not to demand payment from the guarantor first, it is permitted.

הלכה ו
יִשְׂרָאֵל שֶׁלָּוָה מָעוֹת מִן הָעַכּוּ''ם בְּרִבִּית וּזְקָפָן עָלָיו בְּמִלְוֶה וְנִתְגַּיֵּר אִם עַד שֶׁלֹּא נִתְגַּיֵּר זְקָפָן עָלָיו בְּמִלְוֶה גּוֹבֶה אֶת הַקֶּרֶן וְהָרִבִּית וְאִם מִשֶּׁנִּתְגַּיֵּר זְקָפָן עָלָיו בְּמִלְוֶה גּוֹבֶה אֶת הַקֶּרֶן וְלֹא אֶת הָרִבִּית. אֲבָל עַכּוּ''ם שֶׁלָּוָה מִיִּשְׂרָאֵל בְּרִבִּית וְזָקַף עָלָיו אֶת הָרִבִּית בְּמִלְוֶה אַף עַל פִּי שֶׁזְּקָפָן עָלָיו אַחֵר שֶׁנִּתְגַּיֵּר גּוֹבֶה אֶת הַקֶּרֶן וְאֶת הָרִבִּית שֶׁלֹּא יֹאמְרוּ בִּשְׁבִיל מְעוֹתָיו נִתְגַּיֵּר זֶה. וְגוֹבֶה הַיִּשְׂרָאֵל מִמֶּנּוּ אַחַר שֶׁנִּתְגַּיֵּר כָּל מְעוֹת הָרִבִּית שֶׁנִּתְחַיֵּב בָּהֶן כְּשֶׁהָיָה עַכּוּ''ם:
כסף משנה
6.
The following laws apply when a Jew borrowed money from a gentile at interest and then the gentile converted. If a reckoning was made before he converted, the convert may collect the principal and the interest. If a reckoning was not made until after he converted, the convert may collect the principal, but not the interest.
Different rules apply when, by contrast, a gentile borrows money from a Jew at interest and then converts. After a reckoning is made, even if it was made after the conversion, the convert is required to pay the entire sum, the principal and the interest. This measure was instituted lest people say that the person converted for the sake of his money. Even after he converted, the Jew can collect the entire sum of interest for which he became liable while he was a gentile.

הלכה ז
מִצְוָה לְהַקְדִּים הַלְוָאַת יִשְׂרָאֵל בְּחִנָּם לְהַלְוָאַת עַכּוּ''ם בְּרִבִּית:
כסף משנה
7.
It is a mitzvah to lend money to a Jew without charge before lending money to a gentile at interest.

הלכה ח
אָסוּר לְאָדָם שֶׁיִּתֵּן מְעוֹתָיו קָרוֹב לְשָׂכָר וְרָחוֹק לְהֶפְסֵד שֶׁזֶּה אֲבַק רִבִּית הוּא וְהָעוֹשֶׂה כֵן נִקְרָא רָשָׁע. וְאִם נָתַן חוֹלְקִין בַּשָּׂכָר וּבַהֶפְסֵד כְּדִין הָעֵסֶק. וְהַנּוֹתֵן מְעוֹתָיו קָרוֹב לְהֶפְסֵד וְרָחוֹק לְשָׂכָר הֲרֵי זֶה נִקְרָא חָסִיד:
כסף משנה
8.
It is forbidden for a person to invest his money in a manner where his share in the profit is great and his share in the eventuality of loss is minimal. This is considered "the shade of interest." A person who makes such investments is considered "wicked."
If a person makes such an investment, the profits and the losses are divided according to the laws governing a hetter iska. A person who invests his money in a manner where his share in the profit is minimal and his share in the eventuality of loss is great is considered pious.

הלכה ט
אֵין מוֹשִׁיבִין חֶנְוָנִי לְמַחֲצִית שָׂכָר וְלֹא יִתֵּן מָעוֹת לִקַּח בָּהֶן פֵּרוֹת לְמַחֲצִית שָׂכָר וְלֹא בֵּיצִים לְהוֹשִׁיב תַּחַת הַתַּרְנְגוֹלִין שֶׁלּוֹ לְמַחֲצִית שָׂכָר וְאֵין שָׁמִין עֲגָלִים וּסְיָחִין לְפַטְּמָן לְמַחֲצִית שָׂכָר אֶלָּא אִם כֵּן נָתַן לוֹ שְׂכַר עֲמָלוֹ וּמְזוֹנוֹ. אוֹ יִהְיֶה רֶוַח הַמִּתְעַסֵּק יוֹתֵר עַל הֶפְסֵדוֹ כְּמוֹ שֶׁבֵּאַרְנוּ בְּעִנְיַן הַשֻּׁתָּפוּת:
כסף משנה
9.
We may not appoint a person as a storekeeper in return for half of the profits, nor may one entrust a person with money to buy produce in return for half of the profits, nor may one buy eggs to place under another person's chickens in return for half of the profits, nor may one evaluate calves and young donkeys and then have them fattened in return for half of the profits.
These arrangements are permitted only when the investor pays the manager a wage for his efforts and reimbursement for the upkeep of the animals, or grants the manager a greater share of the profits than his share in the event of a loss, as we explained with regard to partnerships.

הלכה י
הַמִּשְׁתַּתֵּף עִם חֲבֵרוֹ בְּמָעוֹת אוֹ בְּקַרְקַע אוֹ הַנּוֹתֵן לוֹ עֵסֶק לֹא יְצָרֵף הַשָּׂכָר עִם הַקֶּרֶן שֶׁמָּא לֹא יִהְיֶה שָׁם שָׂכָר וְנִמְצְאוּ בָּאִין לִידֵי רִבִּית. וְכֵן לֹא יִתֵּן לוֹ מָעוֹת בְּתוֹרַת עֵסֶק אוֹ שֻׁתָּפוּת וְיִכְתֹּב אוֹתָן מִלְוֶה שֶׁמָּא יָמוּת וְנִמְצָא הַשְּׁטָר בְּיַד הַיּוֹרֵשׁ וְגוֹבֶה בּוֹ אֶת הָרִבִּית:
כסף משנה
10.
When a person enters into a partnership arrangement with a colleague, entrusting him with money or with land, or making an iska agreement, he should not include the profit together with the principal as a single sum in the promissory note, lest there be no profit and this lead to interest.
Similarly, a person should not give a colleague money as an iska or in a partnership, but have a promissory note written as if it were a loan. This is prohibited lest he die and the promissory note be given to his heir, who will use it to collect interest.

הלכה יא
אָסוּר לְהַקְדִּים הָרִבִּית אוֹ לְאַחֵר אוֹתוֹ. כֵּיצַד. נָתַן עֵינָיו לִלְווֹת מִמֶּנּוּ וְהָיָה מְשַׁלֵּחַ לוֹ סִבְלוֹנוֹת בִּשְׁבִיל שֶׁיַּלְוֵהוּ זוֹ הִיא רִבִּית מֻקְדֶּמֶת. לָוָה מִמֶּנּוּ וְהֶחְזִיר לוֹ מְעוֹתָיו וְהָיָה מְשַׁלֵּחַ לוֹ סִבְלוֹנוֹת בִּשְׁבִיל מְעוֹתָיו שֶׁהָיוּ בְּטֵלִין אֶצְלוֹ זוֹ הִיא רִבִּית מְאֻחֶרֶת. וְאִם עָבַר וְעוֹשֶׂה כֵן הֲרֵי זֶה אֲבַק רִבִּית:
כסף משנה
11.
It is forbidden to pay interest before taking a loan or to pay it afterwards. What is implied? If a person thought about receiving a loan from a colleague and sent him presents so that he would grant him the loan, this is considered to be paying interest before giving a loan. If he took a loan from him and returned the debt, and then sent the lender a present for the fact that his money was in his possession without his receiving any benefit, this is considered as paying interest afterwards. If one transgresses and does this, this is "the shade of interest."

הלכה יב
מִי שֶׁלָּוָה מֵחֲבֵרוֹ וְלֹא הָיָה רָגִיל מִקֹּדֶם לְהַקְדִּים לוֹ שָׁלוֹם אָסוּר לְהַקְדִּים לוֹ שָׁלוֹם. וְאֵין צָרִיךְ לוֹמַר שֶׁיְּקַלְּסוֹ בִּדְבָרִים אוֹ יַשְׁכִּים לְפִתְחוֹ שֶׁנֶּאֱמַר (דברים כג כ) "נֶשֶׁךְ כָּל דָּבָר" אֲפִלּוּ דְּבָרִים אֲסוּרִים. וְכֵן אָסוּר לוֹ לְלַמֵּד אֶת הַמַּלְוֶה מִקְרָא אוֹ גְּמָרָא כָּל זְמַן שֶׁמְּעוֹתָיו בְּיָדוֹ אִם לֹא הָיָה רָגִיל בָּזֶה מִקֹּדֶם שֶׁנֶּאֱמַר נֶשֶׁךְ כָּל דָּבָר:
כסף משנה
12.
When a person who borrowed money from a colleague would not ordinarily greet him first, it is forbidden for him to greet him first. Needless to say, it is forbidden for him to praise the lender in public or go to his home. These prohibitions are derived from the phrase Deuteronomy 23:20: "All types of neshech"; even words are forbidden.
Similarly, it is forbidden for the borrower to teach the lender Scripture or Talmud throughout the duration of the loan if the borrower was not accustomed to doing so previously, as implied by the phrase: "All types of interest."

הלכה יג
הַמַּלְוֶה אֶת חֲבֵרוֹ לֹא יֹאמַר לוֹ דַּע אִם בָּא אִישׁ פְּלוֹנִי מִמָּקוֹם פְּלוֹנִי (כְּלוֹמַר) שֶׁתְּכַבְּדוֹ וְתַאֲכִילוֹ וְתַשְׁקֵהוּ כָּרָאוּי. וְכֵן כָּל כַּיּוֹצֵא בָּזֶה:
כסף משנה
13.
When a person lends money to a colleague, he should not tell the borrower: "Take notice if so and so from this and this place comes." Implied is that the borrower should honor him and provide him with food and drink as is appropriate. Similar laws apply in all analogous situations.

הלכה יד
יֵשׁ דְּבָרִים שֶׁהֵן כְּמוֹ רִבִּית וּמֻתָּרִין כֵּיצַד. לוֹקֵחַ אָדָם שִׁטְרוֹתָיו שֶׁל חֲבֵרוֹ בְּפָחוֹת וְאֵינוֹ חוֹשֵׁשׁ. וּמֻתָּר לְאָדָם לִתֵּן לַחֲבֵרוֹ דִּינָר כְּדֵי שֶׁיַּלְוֶה לִפְלוֹנִי מֵאָה דִּינָרִין שֶׁלֹּא אָסְרָה תּוֹרָה אֶלָּא רִבִּית הַבָּאָה מִן הַלּוֶֹה לַמַּלְוֶה. וְכֵן אוֹמֵר אָדָם לַחֲבֵרוֹ הֵא לְךָ דִּינָר זֶה וֶאֱמֹר לִפְלוֹנִי שֶׁיַּלְוֵנִי. שֶׁלֹּא נָתַן אֶלָּא שְׂכַר אֲמִירָה:
כסף משנה
14.
There are practices that resemble interest, but which are permitted. What is implied? A person may purchase a promissory note from a colleague for less than its face value without any concern. A person may give a colleague a dinar so that he will lend a third party 100 dinarim. The rationale is that the Torah forbade only interest given by the borrower to the lender.
Similarly, a person may tell a colleague: "Here is a dinar. Tell so and so to give me a loan." This is permitted, because he gave him a wage only for making the suggestion.

הלכה טו
יֵשׁ דְּבָרִים שֶׁהֵן מֻתָּרִין וְאָסוּר לַעֲשׂוֹתָן מִפְּנֵי הַעֲרָמַת רִבִּית. כֵּיצַד. אָמַר לוֹ הַלְוֵנִי מָנֶה אָמַר לוֹ מָנֶה אֵין לִי חִטִּים יֵשׁ לִי בְּמָנֶה וְנָתַן לוֹ חִטִּים בְּמָנֶה וְחָזַר וּלְקָחָן מִמֶּנּוּ בְּתִשְׁעִים הֲרֵי זֶה מֻתָּר. אֲבָל אֲסָרוּהוּ מִפְּנֵי הַעֲרָמַת רִבִּית שֶׁהֲרֵי נָתַן לוֹ תִּשְׁעִים וְלוֹקֵחַ מָנֶה. וְאִם עָבַר וְעָשָׂה כָּזֶה הֲרֵי הוּא מוֹצִיא מִמֶּנּוּ מֵאָה בְּדִין שֶׁאֲפִלּוּ אֲבַק רִבִּית אֵין כָּאן. וְכֵן מִי שֶׁהָיְתָה שָׂדֶה מְמֻשְׁכֶּנֶת בְּיָדוֹ לֹא יַחְזֹר וְיַשְׂכִּיר אוֹתָהּ לְבַעַל הַשָּׂדֶה מִפְּנֵי הַעֲרָמַת רִבִּית שֶׁהֲרֵי זֶה עוֹמֵד בְּשָׂדֵהוּ כְּשֶׁהָיָה וְנוֹתֵן לָזֶה שָׂכָר בְּכָל חֹדֶשׁ בִּשְׁבִיל מְעוֹתָיו שֶׁהִלְוָהוּ:
כסף משנה
15.
There are certain matters that are permitted, and yet are forbidden because they are ha'aramat ribit (a circumvention of the prohibition against interest).
What is implied? The borrower tells the lender: "Lend me a maneh." The lender answers: "I do not have a maneh. I have wheat worth a maneh," and he gave him the wheat for a maneh and then purchased it from him for 90 zuz. This is permitted, but it was forbidden by the Sages as a circumvention of the prohibition against interest. For he gave him 90 and received a maneh.
If the lender transgressed and carried out these transactions, the lender may expropriate 100 zuz from the borrower through legal process, because even "the shade of interest" is not involved. Similarly, if a field was given as security for a loan, the lender may not rent it back to the owner of the field, because this is a circumvention of the prohibition against interest. For the borrower is receiving the field that he owned and paying the lender rent each month because he lent him money.

הלכה טז
אָסוּר לְהַשְׂכִּיר הַדִּינָרִין שֶׁאֵין זֶה דּוֹמֶה לְמַשְׂכִּיר אֶת הַכְּלִי שֶׁהַכְּלִי חוֹזֵר בְּעַצְמוֹ וְזֶה מוֹצִיא אֵלּוּ וּמֵבִיא דִּינָרִין אֲחֵרוֹת וְנִמְצָא זֶה אֲבַק רִבִּית:
כסף משנה
16.
It is forbidden to hire out dinarim. This does not resemble hiring out other utensils. In the latter case, the same utensil that was hired out is returned, In this instance, however, the recipient spends the dinarim he receives and pays him back with others. Hence, "the shade of interest" is involved.

הלכה יז
מֶלֶךְ שֶׁהָיוּ דִּינָיו שֶׁכָּל מִי שֶׁיִּתֵּן הַמַּס הַקָּצוּב עַל כָּל אִישׁ וְאִישׁ עַל יְדֵי זֶה שֶׁלֹּא נָתַן יִשְׁתַּעְבֵּד בּוֹ וְנָתַן עַל יָדוֹ דִּינָר אַף עַל פִּי שֶׁמְּשַׁעְבֵּד בּוֹ יֶתֶר מִדִּינָר הֲרֵי זֶה מֻתָּר. וְכֵן כָּל כַּיּוֹצֵא בָּזֶה:
כסף משנה
17.
The following rules apply when a king has established a law that whoever pays the head tax imposed on every person for a particular person has the right to take control of that person and treat him as a serf. If a person pays a dinar as the tax for a particular person and then has him work for more than a dinar, this is permitted. Similar principles apply in all analogous situations.

משפטים הלכות מלווה ולווה פרק ה
Mishpatim Malveh and Loveh Chapter 5