Related for Shabbat 162:4
א"ר יוחנן אסור לקנח בחרס בשבת מאי טעמא אילימא משום סכנה אפילו בחול נמי ואלא משום כשפים אפי' בחול נמי לא ואלא משום השרת נימין דבר שאין מתכוין הוא אמר להו רב נתן בר אושעיא גברא רבה אמר מילתא נימא בה טעמא לא מיבעיא בחול דאסור אבל בשבת הואיל ואיכא תורת כלי עליו שפיר דמי קמ"ל
R. Kahana demurred: If they said [that it is permitted] in case of need,<span class="x" onmousemove="('comment',' Sc. for cleansing, which is necessary. ');"><sup>12</sup></span> shall they say [thus] where there is no need!<span class="x" onmousemove="('comment',' Surely not! ');"><sup>13</sup></span> Abaye said: As for parpisa, since it has come to hand, we will state something about it. If it is lying on the ground and one places it upon pegs, he is culpable on the score of detaching; if it is lying on pegs and one places it on the ground, he is liable on the score of planting.<span class="x" onmousemove="('comment',' Cf. n. 3. 'Culpable' here merely denotes that the action is forbidden, but does not imply liability to a sin-offering, as usual (Rashi and Tosaf.). ');"><sup>14</sup></span> R. Johanan said: One must not cleanse oneself with a shard on the Sabbath. What is the reason? Shall we say on account of danger?<span class="x" onmousemove="('comment',' He may cut himself. ');"><sup>15</sup></span>