Reference for Sanhedrin 135:9

מנעל שעל גבי האמוס מהו אמר להן הוא טהור ויצאה נשמתו בטהרה עמד רבי יהושע על רגליו ואמר הותר הנדר הותר הנדר

Much Torah have I learnt, yet have I but skimmed from the knowledge of my teachers as much as a dog lapping from the sea. Much Torah have I taught, yet my disciples have only drawn from me as much as a painting stick from its tube. Moreover, I have studied three hundred laws on the subject of a deep bright spot,<span class="x" onmousemove="('comment',' One of the forms of leprosy, Lev. XII, 2. ');">⁹</span>

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