Responsa for Nedarim 72:9

מלמדו מדרש הלכות ואגדות אבל לא ילמדנו מקרא: מקרא מאי טעמא לא ילמדנו משום דקמהני ליה מדרש נמי קמהני ליה אמר שמואל במקום שנוטלין שכר על המקרא ואין נוטלין שכר על המדרש מאי פסקא

Do we say, but for this man's produce, would the other's stack have been made fit to use?<span class="x" onmousemove="('comment',' Therefore the goodwill should belong to him who renders the terumah. ');">⁹</span> Or perhaps, but for this man's stack, the other man's produce would not be <i>terumah</i>?<span class="x" onmousemove="('comment',' Produce can he declared terumah only on account of other produce. But one cannot take some corn and declare it terumah. ');">¹⁰</span> — He replied, Scripture saith, all the increase of thy seed&nbsp;… and thou shalt give.<span class="x" onmousemove="('comment',' Deut. XIV, 25. In its context, thou shalt give refers to the changing of produce into money; but it is here taken out of its context and related to all the increase of thy seed, shewing that the goodwill belongs to the owner of the corn, no matter who actually separates the tithe. This is the reading of our text, and also that of Ran. But such forcible disregard of the context is not very plausible. Asheri prefers a preferable reading: (When thou hast made an end of tithing) All the tithes of thine increase&nbsp;… and thou shalt give it to the Levite; (Deut. XXVI, 12). ');">¹¹</span> He objected: HE MAY SEPARATE HIS <i>TERUMAH</i> AND HIS TITHES WITH HIS CONSENT. Now if you say that the goodwill belongs to the owner, surely he [the maddir] benefits him? Hence this proves that the goodwill is his!<span class="x" onmousemove="('comment',' This of course is on the assumption that the naddir gives his own corn as terumah. ');">¹²</span> — I will tell you: it is not so. This means that the <i>terumah</i> belongs to the owner; 'HIS CONSENT also referring to the owner, who had announced, 'Whoever wishes to separate, let him do so.' Come and hear: R. Abbahu said in R. Johanan's name: He who sanctifies the animal must add the fifth, whilst only he for whom atonement is made sanctifies a substitute;<span class="x" onmousemove="('comment',' If A dedicates an animal for B's sacrifice and it subsequently receives a blemish and must be redeemed, then if A, who sanctified it, redeems it himself, he must add a fifth to its value, but nut if B redeems it (this is deduced from Lev. XXVII, 15). Again, if another animal is substituted for the first, both the original and its substitute are holy (ibid. 10). R. Johanan rules that this is only if B, on whose behalf the animal was sanctified, made the substitution, but not if A did so. ');">¹³</span> and he who gives <i>terumah</i> of his own for another man's produce, the goodwill is his.<span class="x" onmousemove="('comment',' Sc. the man who gives it. ');">¹⁴</span> HE MAY TEACH HIM MIDRASH, HALACHOTH, AND AGGADOTH, BUT NOT SCRIPTURE. Why not Scripture — because he benefits him? But [by] Midrash too he benefits him? — Said Samuel: This refers to a place where the teaching of Scripture is remunerated, but not that of Midrash. How state this definitely?<span class="x" onmousemove="('comment',' Seeing that the statement in the Mishnah is unqualified. ');">¹⁵</span> —

Teshuvot Maharam