Related for Bekhorot 121:37
ומאי שנא מהא דתנן
or increased it by ten, his terumah is valid!<span class="x" onmousemove="('comment',' Ter. IV, 4. Why cannot the owner say here, as R. Papa maintains above, that the one in forty which the agent separated as terumah was a mistake which caused him a loss and that therefore his agency is void?');"><sup>25</sup></span>
Tosefta Terumot
[If an owner] says to his agent, "Go and separate terumah!", he separates an average amount, one fiftieth. [If the owner says] "Go and separate terumah, one fiftieth!" and [the agent inadvertently] reduces it by ten [parts] or increases it by ten [parts], his terumah is [valid] terumah, but if he intended to add [even] one [part more], his terumah is not [valid] terumah. (Ter. 4:4.)
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