Responsa for Yevamot 201:7
אמר רב פפא הכי קאמר אם היו שניהם משמר אחד ובית אב אחד נוטל חלק אחד:
he is driven away and<span class="x" onmousemove="('comment',' Cf. MS.M. and BaH. Cur. edd. omit to the end of the sentence. ');"><sup>21</sup></span> when he comes to the other beth ab he is also driven away! — R. Papa replied: It is this that was meant: IF, HOWEVER, BOTH SERVED IN THE SAME MISHMAR and in the same beth ab, HE RECEIVES A SINGLE PORTION. MISHNAH. THE COMMANDMENT OF <i>HALIZAH</i> MUST BE PERFORMED IN THE PRESENCE OF THREE JUDGES, EVEN THOUGH ALL THE THREE ARE LAYMEN.<span class="x" onmousemove="('comment',' Not professional judges. ');"><sup>22</sup></span> IF THE WOMAN PERFORMED THE <i>HALIZAH</i> WITH A SHOE,<span class="x" onmousemove="('comment',' Made of soft leather and covering the upper part of the foot (cf. Rashi and Jast.) opp. to sandal (v. infra n. 3). ');"><sup>23</sup></span>
Teshuvot Maharam
A. Bediabad, in this case, means after the rite was performed. Nevertheless, the aforementioned performance of the rite is invalid, for a different reason: the shoe used was sewed with flaxen thread and, therefore, was never fit for this purpose. Since, however, the levir performed an invalid rite of halitzah, neither he nor his brothers are now permitted to marry the widow. Halitzah by the same levir being the only manner of releasing her, he may be forced, by persuasion or by flagellation, to repeat the rite with the proper shoe. For now the Mitzvah revolved on him alone, and we are permitted to scourge a Jew until he perform the required Mitzvot.
This Responsum is addressed to Rabbi Menahem of Würzburg.
SOURCES: Am I, 93, 94.