Quotation for Shabbat 215:7

מניין למילה שבאותו מקום נאמר כאן ערלתו ונאמר להלן ערלתו מה להלן דבר שעושה פרי אף כאן דבר שעושה פרי אימא לבו דכתיב (דברים י, טז) ומלתם את ערלת לבבכם אימא אזנו דכתיב (ירמיהו ו, י) הנה ערלה אזנם דנין ערלתו תמה מערלתו תמה ואין דנין ערלתו תמה מערלת שאינה תמה

How do we know that circumcision [must be performed] in that [particular] place? — 'His 'orlah'<span class="x" onmousemove="('comment',' Gen. XVII, 14, in connection with circumcision (E.V. foreskin). ');">¹⁶</span> is stated here, and 'its 'orlah'<span class="x" onmousemove="('comment',' Lev. XIX, 23, in reference to the fruit of a tree within the first three years of its planting, which may not be eaten (E.V. uncircumcision). ');">¹⁷</span> is stated elsewhere: just as there something that produces fruit [is meant], so here too something [the limb] that produces fruit [is meant]. Perhaps it means the heart, for it is written, Circumcise therefore the foreskin of your heart?<span class="x" onmousemove="('comment',' Deut. X, 16. This question of course was not mentioned seriously, but was put merely to point out that 'circumcision' is mentioned in connection with other organs too. ');">¹⁸</span>

Mishnah Kelim