Reference for Shevuot 28:15

בעי רבי ירמיה בן בבל שעלה לארץ ישראל ונעלם ממנו מקום מקדש מהו

[Shall we say] since he knew that a reptile contaminates, this is counted knowledge; or, since he did not know whether the size of a lentil contaminates or not, it is counted as unawareness?<span class="x" onmousemove="('comment',' Therefore, there is no knowledge at the beginning.');">²²</span> - The question remains undecided.<span class="x" onmousemove="('comment',' Lit., 'Let it stand'.');">²³</span>

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