Reference for Zevachim 105:13

בשלמא למאן דאמר יסוד מערבי קסבר ילמד סתום מן המפורש

Did the horns occupy four cubits?<span class="x" onmousemove="('comment',' Since each was a cubit in length, actually only two cubits of the length or the breadth of the altar were occupied by the horns.');">¹⁶</span> - Say rather: The limits of the horns were four [cubits].<span class="x" onmousemove="('comment',' A distance of four cubits below the horns, i.e., as far down as the scarlet line, still ranked as the horns. Therefore Rabbi says that the upper blood, i.e., the blood which is sprinkled on the horn, can be sprinkled anywhere above the scarlet line.');">¹⁷</span>

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