The Torah prohibition of Ri’bitt forbids lending on interest. The Shulhan Aruch (Yoreh Dei’a 160:13) restricts this prohibition to cases where the borrower himself pays the lender compensation for allowing him to retain his money for a period of time. A lender may, however, receive payment for the loan from a third party. Thus, as Rabbi Moshe Halevi writes in his work Milveh Hashem (p. 138), it is permissible to pay somebody to give a loan to one’s friend, and this does not violate the prohibition of Ri’bitt. In such a case, however, the third party may not then approach the borrower and demand that he be compensated for the money he expended on the borrower’s behalf. Since the borrower will then be indirectly paying the lender for granting him a loan, this would constitute Ri’bitt.
Rabbi Moshe Ha’levi notes that according to some authorities, it is forbidden for the borrower to initiate this arrangement, by approaching the third party and asking him to offer money to a lender so that he would agree to give a loan. The Shulhan Aruch, however, does not follow this view, and thus it is permissible for a person in need of a loan to ask his friend to approach a potential lender and offer money for the loan.
Summary: A third party may pay a person to lend to his friend, and the borrower may even initiate this arrangement by asking a friend to approach a potential lender and offer money for the loan. However, the third party may not then demand that the borrower compensate him for this expenditure.