Concerning both cases, R. Joshua [T2] said: `this is not the kind of Terumah over which I am cautioned lest I defile it, but lest I eat of it.` of which [was it cautioned] `that thou must not defile it`? If one was passing from place to place with loaves of Terumah in his hand and a Gentile said to him: `give me one of these and I will make it unclean; for if not, I will defile them all`, let him defile them all, and not give him deliberately one to defile. But R. Joshua [T2] says: He should place one of them on a rock.
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So also in the case of two upper storeys opposite each other the tenants of one of which made a trough and those of the other did not, those who made the trough are permitted to pour down their water, whereas those who did not make any trough are forbidden.
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