Reference for Sanhedrin 175:14

משום רבי ישמעאל אמרו אף מפריש מן העיסה:

R. Eliezer said: From his [sc. the victim's] navel. R. Akiba said: From his nose. R. Eliezer b. Jacob said: From the place where he becomes a murdered corpse. Viz., the neck.<span class="x" onmousemove="('comment',' Sotah 45b. The easiest form of murder is by slitting the throat. Now, if one gives this heifer as kiddushin, it is invalid. Consequently, if of two towns one is nearest the victim's navel, and the other to his nose, and each assigned a heifer (one of which of course is invalid), one is fit for kiddushin, and the other is not; v. p. 579. n. 3. ');">¹⁴</span>

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