Reference for Pesachim 169:7

אביי אמר משום פקע רבינא אמר בקולית

Let us scrape a little away and break it? - Abaye said: [This cannot be done] because of a [possible] split.<span class="x" onmousemove="('comment',' When he hits the bone to break it, it may split elsewhere, not just where it was scraped.');">⁸</span> Rabina said: This refers to the thigh bone.<span class="x" onmousemove="('comment',' Which contains marrow; hence scraping the flesh off is of no avail.');">⁹</span>

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