Our Gemara quotes a baraita that rejects the simple interpretation of the passage in Sefer (25:9) – ve-haltzah na’alo me’al raglo – which seemingly requires the removal of the yavam’s own personal shoe. The baraita’s interpretation of the pasuk is that it must be a shoe that is appropriate for him, which excludes a shoe that is so big on him that he cannot walk, or one so small that it will not cover most of his foot. It also excludes a sandal hamesulyam she-en lo akev.
Rashi explains that a sandal hamesulyam she-en lo akev is a sandal with no sole.
According to the Aruk and the Ge’onim, the correct reading in the Gemara is sandal hamesulyas, which comes from the Latin soleas, a type of sandal that is open in the back and does not hold the back of the foot (similar to modern flip-flops). The mitzva of halitza is for the yevama to remove the yavam’s heel from the shoe, so an open-backed sandal is not appropriate for the mitzva.
To illustrate the halakha of ownership of the shoe, the Gemara tells of a halitza that took place in the presence of Abaye and Rav Yosef. Rav Yosef asked Abaye to offer his own shoe to the yavam. Abaye offered his left shoe, which was rejected by Rav Yosef, who argued that the Mishna (104a) only permits the use of the left shoe be-di’eved (after the fact), but that ideally the right one should be used. Abaye responded by saying that although someone else’s shoe can be used, ideally the yavam should use his own. Rav Yosef responded that he, in fact, intended that Abaye should offer his shoe to the yavam as a present.
As we noted on yesterday’s daf, today every Jewish court that arranges for a halitza has a special halitza shoe. The Shulhan Aruk (Even ha-Ezer 169:14) rules that the shoe should be given to the yavam as a gift before halitza so it will belong to him during halitza, in order to satisfy Rav Yosef’s ruling.