Reference for Eruvin 70:7

וסבר רבי מאיר תחומין דאורייתא והא תנן אם אין יכול להבליעו בזו אמר רבי דוסתאי בר ינאי משום ר"מ שמעתי שמקדרין בהרים

as, for instance, where one ate unclean foods or drank unclean liquids or where a man immersed<span class="x" onmousemove="('comment',' Lit., 'and he came'.');">¹³</span> his head and the greater part of his body in drawn water, or three log of drawn water were poured upon his head and the greater part of his body<span class="x" onmousemove="('comment',' Thus rendered unclean by Rabbinic law; v. Shab. 14a.');">¹⁴</span>

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