Reference for Kiddushin 7:21

אלא אמר מר בר רב אשי לא נצרכה אלא לעיקר זבינא דאילונית סד"א דאתיא סימני נערות הוי זבינא דלא אתיא סימני נערות לא הוי זבינה זבינא

I might have thought, she [a Hebrew maidservant] is freed only by na'aruth, but not by bagruth: hence we are informed [otherwise]. Mar, son of R'Ashi, demurred: But does this not follow a minori? If symptoms [of na'aruth], which do not free her from parental authority,<span class="x" onmousemove="('comment',' V. p. 7.');">²⁷</span> free her from her master's authority: then bagruth, which liberates from parental authority, surely liberates her from her master's authority! - But, said Mar, son of R'Ashi: This is necessary only in respect of the sale itself of barren woman:<span class="x" onmousemove="('comment',' I.e., a minor who shews symptoms of constitutional barrenness.');">²⁸</span> I might have thought, with one who will [subsequently] produce evidence of na'aruth, the sale is valid: but with one who will not produce such evidence<span class="x" onmousemove="('comment',' V. n. 5.');">²⁹</span> the sale is altogether invalid:

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