Reference for Shabbat 131:14
אמר מר סנדל של סיידין טמא מדרס הא לאו להילוכא עבדי אמר רב אחא בר רב עולא שכן הסייד מטייל בו עד שמגיע לביתו:
R. Joseph observed: Since Samuel said: A stump-legged person may not [etc.], and R. Huna [also] said: A stump-legged person may not [etc.], then we too should learn, A stump-legged person may not. Rabbah b. Shila demurred: Did they not hear what R. Hanan b. Raba recited to Hiyya b. Rab before Rab in a little room of Rab's academy: A stump-legged person may not go out with his wooden stump: this is R. Meir's view; but R. Jose permits it; whereupon Rab signalled to them that it was the reverse? R. Nahman b. Isaac observed: And your token is samek samek.<span class="x" onmousemove="('comment',' Samek (x) is a letter of the Hebrew alphabet. Thus R. Jose (hxuh) forbids (rxut), the samek occurring in the name and in the ruling. ');"><sup>14</sup></span>