842. A Utensil With a Permitted Purpose

Shabbos 24:13

When a person looks for and transports items that are used for purposes prohibited on Shabbos, the possibility exists that he may come to use them and perform an act of labor. Also, some people are not craftsmen and are always unoccupied, like those who loiter on street corners. If such people, who never work, were permitted to walk, talk and carry as they do during the week, there would no visible difference between their Shabbos and their weekdays. For this reason, the Sages enacted that we refrain from such things, which apply to everyone. These are the reasons for the rules against carrying certain things on Shabbos. The Sages prohibited carrying on Shabbos, excluding items that will be needed, as we shall see.

Shabbos 25:1

Some utensils are intended for uses that are permitted on Shabbos; these may be used in the same manner on Shabbos as during the week. Such utensils include a cup for drinking, a bowl for eating, a knife to cut meat or bread, a nutcracker, etc.