Reference for Sanhedrin 151:3

ולמאן דאמר סקילה חמורה מהאי קושיא לא נידונה

Whilst on the view that stoning is severer, the analogy cannot be made on account of this last difficulty.<span class="x" onmousemove="('comment',' Since according to this comparison incest with his maternal grandmother is punished by burning. But his maternal grandmother should also be compared to his mother, the punishment for which is stoning; hence the entire analogy falls to the ground. ');">³</span>

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