837. Waiting By the Techum
Shabbos 24:3
The rule that one may not wait by the Shabbos boundary (techum) for Shabbos to end only applies when one is waiting to perform an activity that is prohibited on Shabbos. It is permitted to wait at the Shabbos boundary for Shabbos to end in order to perform an activity that is permitted on Shabbos. For example, one may not wait at the boundary for Shabbos to end so that he can bring in produce that is still attached to the ground or hire workers but one may go wait at the boundary in order to guard his produce because this is permitted to do on Shabbos. Similarly, one may go and wait for Shabbos to end in order to bring an animal or produce that has already been detached from the ground. This is because one is permitted to call an animal so that it will come even from beyond the Shabbos boundary and, if there had been structures, one would have been able to bring detached produce in on Shabbos (so these things are not inherently prohibited). Similarly, one person may tell another that he is traveling to another city after Shabbos because if there had been enough buildings in between, he would have been permitted to walk there on Shabbos. The same is true in all comparable circumstances.
Shabbos 24:4
If a person sees an employee on Shabbos, he is permitted to tell him to stick around after Shabbos (even though his meaning is understood) but he may not tell him to be prepared for after Shabbos because by doing so the employer addresses his business concerns too directly. One is not permitted to run or jump on Shabbos as per Isaiah 58:13, which tells us to refrain from our usual activities on Shabbos; the way we walk on Shabbos should not be like the way we walk during the week. One may, however, descend into a well, pit or cave even 100 cubits deep (150 ft.) in order to drink and then climb back up. We are not permitted to speak at length about mundane things because the way in which we speak on Shabbos should not be the same as the way in which we speak during the week (ibid.).