Halakhah su Ecclesiaste 7:19

From the laws of the commandment is that which they, may their memory be blessed, said (Bava Metzia 71a) that it is a commandment to prioritize a free loan to an Israelite over lending to a gentile with interest; and that which they said (Bava Metzia 72a and see Mishneh Torah, Creditor and Debtor 5:1) that [if] a gentile borrowed money from an Israelite with interest - even though he converted - [the Israelite] should collect from him all the interest that accrued until he converted; so that they will not say, "He converted to not pay the interest." And in the same manner that we were commanded to request interest from them, so too is it permissible to give them interest; since the verse only prohibited [taking] interest of an Israelite - the matter is known. And they, may their memory be blessed, said (Bava Metzia 71b and see Mishneh Torah, Creditor and Debtor 5:4) that [if] a gentile borrowed money from an Israelite and wanted to pay back [the loan] and found another Israelite and [that Israelite] said, "Give it to me and I will give you the interest from it, in the [same] way that you give it to the Israelite," it is permissible. But if [the gentile] stood [this Israelite] in front of the Israelite [lender] - even though the gentile gives the money to the hand of [the Israelite borrower] - since [the gentile] gave the money with the knowledge of the Israelite [lender], behold it is fixed interest (and forbidden). And they, may their memory be blessed, said (Bava Metzia 70b and see Mishneh Torah, Creditor and Debtor 5:2) that even though their interest is permissible according to the [letter of the] law, it is [still] forbidden for an Israelite to lend to them with fixed interest, more than what he needs for his livelihood; so that he not be accustomed to always be with him and learn from his deeds. But it is permissible to take 'the dust of interest (avak ribit),' even if it is more than what he needs for his livelihood - since he will not be so accustomed to be with him for the sake of the 'dust of interest.' And a Torah scholar may lend whatever he wants, as there is no concern about him that he will learn from [the gentile's] deeds; since 'wisdom emboldens the sage and guards him forever.' And the rest of its details are elucidated in the chapter [entitled] Eizehhu Neshekh in Bava Metzia (see Tur, Yoreh Deah 159, 160).