Reference for Eruvin 71:16
א"ל לכי תיכול עליה כורא דמלח' היום חול ולמחר קדש מספיקא לא נחתא ליה קדושה היום קדש ולמחר חול מספיקא לא פקעא ליה קדושתיה מיניה
only because if it is assumed that [the terumah] was clean the man knows [where to look for] it,<span class="x" onmousemove="('comment',' And is able, therefore, to eat; the question of its possible uncleanness being disregarded owing to its presumptive cleanness.');"><sup>40</sup></span> but here,<span class="x" onmousemove="('comment',' Since it is not known which of the loaves was the clean one.');"><sup>41</sup></span> surely, he does not know [even where to look for] it?<span class="x" onmousemove="('comment',' In consequence of which he could not eat either of the loaves. The 'erub, since it could not be eaten must, therefore, be ineffective.');"><sup>42</sup></span>