Yoma, Chapter Six, Mishnah Five
This mishnah continues to describe the process of people accompanying the goat on its way to the wilderness.
1) At every booth they would say to him: here is food and here is water.
2) And they went with him from booth to booth, except the last one, who would not go with him up to Zuk, but rather stand from afar, and see what he was doing.
Section one: The task of accompanying the goat to Zuk was considered so important that they allowed the person accompanying the goat to eat or drink on Yom Kippur. It seems that this was likely to have been only a gesture, one meant to emphasize the importance of the task. In reality, the Talmud says that no one ever took them up on their offer. Furthermore, it is hard to imagine that someone entrusted with such a prestigious religious task would risk his reputation by accepting the offer. In any case, even in a theoretical sense, this is an incredible allowance by the rabbis.
Section two: The people from each booth would walk with the person accompanying the goat on his way to the next booth. The one exception was the people from the last booth. Since Zuk was two mils (4000 cubits) from the last booth and one is allowed to walk only 2000 cubits on Shabbat because of the Shabbat border limit, the people from the last booth would accompany the goat only halfway to Zuk. It is interesting to note that in section one the rabbis let the one accompanying the goat eat and drink on Yom Kippur, an obvious infraction of the biblical commandment. In contrast, when it came to those who walked from booth to booth, they seem to have forbade even the rabbinic prohibition (as it is usually understood) of walking beyond 2000 cubits on Shabbat.