Responsa for Bava Metzia 114:4
הכי השתא בשלמא זה חומר בהדיוט מבהקדש ותו לא אלא הקדש זה חומר ותו לא
— That refers to usury. Then it should also teach: In this respect the case of <i>hekdesh</i> is more stringent than that of a layman, viz., overreaching? — How compare? As for saying, 'In this respect the case of a layman is more stringent than that of <i>hekdesh</i>,' it is well, for there are no other [instances].<span class="x" onmousemove="('comment',' [Tosaf. and MS.M. omit 'for there are no other,' since the Mishnah in fact mentions several other instances where greater stringency applies to ordinary property than to that of hekdesh; the reading and argument run accordingly as follows: 'As for saying, " in="" this="" respect="" the="" case="" of="" a="" layman="" is="" more="" stringent="" than="" that="" hekdesh",="" it="" well!="" but="" (with="" to)="" hekdesh,="" (what="" means)="" stringency?'="" whilst,="" to="" say,="" there="" point="" informing="" us="" any="" additional="" instance="" where="" ordinary="" property="" treated="" with="" greater="" stringency="" none="" teaching="" reverse,="" as="" obvious="" regard="" hekdesh="" property.]="" ');"=""><sup>4</sup></span>
Teshuvot Maharam
A. This is undoubtedly prohibited. But since the lending of charity-funds at a definite rate of interest became such a widespread custom throughout the Kingdom that the prohibition of the practice would not be heeded even if the law became known we refrain from publicising this prohibition. This opinion is expressed, however, in order to urge the compliance with this prohibition in the future (but R. Meir would express no opinion as to the necessity of repaying the interest already collected).
SOURCES: Pr. 73; L. 478. Cf. L 234; Cr. 101, 109; Tesh. Maim. Mishpatim, 14; R. Asher, Responsa 13, 8; Agudah B.M. 73.
Teshuvot Maharam
A. B should not give the ten quarter-marks to the poor of that community, since it would constitute unlawful usury. If, however, B earned profit with the ten marks, he must give part of the profit to the poor of another city, since one is not permitted to profit from charity money.
SOURCES: Pr. 999.