Reference for Eruvin 71:9
מאי שנא תרומה דאמר העמד תרומה על חזקתה ואימא טהורה היא פירות נמי העמד טבל על חזקתו ואימא לא נתקנו
the 'erub [is deemed to be one whose validity is in] doubt [and is consequently] effective;<span class="x" onmousemove="('comment',' It being assumed that the terumah was clean and that the fruit was duly prepared during twilight which is the crucial moment for the validity of an 'erub.');"><sup>23</sup></span> but if a man prepared an erub of terumah about which there is doubt whether it was clean or unclean,<span class="x" onmousemove="('comment',' So that the argument of presumptive cleanness is inapplicable.');"><sup>24</sup></span> and so also in the case of fruit concerning which there arose a doubt whether they were prepared [for use] or not<span class="x" onmousemove="('comment',' Cf. previous note mutatis mutandis.');"><sup>25</sup></span>