A bearing includes a main body, a plurality of first magnetic members, a plurality of second magnetic members, and a plurality of friction members. The main body defines a pivot hole, and a plurality of first receiving portions and a plurality of second receiving portions around the pivot hole. Each of the second receiving portions defines a cutout. The first magnetic members are received in the first receiving portions. The second magnetic members together with the friction members are received in the second receiving portions, thus generating a repelling force between the first magnetic members and the second magnetic members to impel the friction members to partially extend out of the cutouts.