Closing device for releasably connecting a first part to a second part, having - a first closing unit, the first closing unit comprising a spherical engaging part and a first retaining device arranged at the spherical engaging part for attaching the first part, and having - a second closing unit, which has a second retaining device for attaching the second part and a cut out (304, 304A) which is delimited by a wall (303, 307A) for receiving the spherical engaging part of the first closing unit, the cut out (304, 304A) of the second closing unit having an opening for inserting the spherical engaging part of the first closing unit, and the spherical engaging part of the first closing unit is held in a closed position of the closing device for the closing of the closing device in the cut out of the second closing unit, wherein - a sliding unit is located in the cut out (304, 304A) of the second closing unit, said sliding unit being preloaded in the direction of the opening of the cut out (304, 304A) of the second closing unit, wherein the sliding unit can be moved into an open position and a closed position along the wall (303, 307A) of the cut out (304, 304A) of the second closing unit in the cut out (304, 304A) of the second closing unit, - in the open position of the sliding unit, the spherical engaging part of the first closing unit can be received in the cut out (304, 304A) of the second closing unit through the opening of the cut out (304, 304A) of the second closing unit, - in the closed position of the sliding unit, the sliding unit delimits an extension of the cut out (304, 304A) of the second closing unit, - in the closed position of the sliding unit and in the closed position of the closing device, the spherical engaging part of the first closing unit lies against both the wall (303, 307A) of the cut out (304, 304A) of the second closing unit and against the sliding unit and is held clamped between the wall (303, 307A) of the cut out (304, 304A) of the second closing unit and the sliding unit, - the spherical engaging part of the first closing unit is magnetic, - a magnetic unit is arranged in the cut out (304, 304A), which interacts with the magnetically formed engaging part of the first closing unit, - the magnetic unit comprises a first outer side and a second outer side, - the first outer side is oriented toward the opening of the cut out (304, 304A), - the second outer side is situated opposite the first outer side, - in the closed position of the sliding unit, the sliding unit is arranged at the second outer side, - the sliding unit has a prolongation, which extends along a side surface of the magnetic unit in the direction of the opening of the cut out (304, 304A), and wherein - the second closing unit comprises a wall cut out, in which the magnetic unit is arranged. - a first closing unit, the first closing unit comprising a spherical engaging part and a first retaining device arranged at the spherical engaging part for attaching the first part, and having - a second closing unit, which has a second retaining device for attaching the second part and a cut out (304, 304A) which is delimited by a wall (303, 307A) for receiving the spherical engaging part of the first closing unit, the cut out (304, 304A) of the second closing unit having an opening for inserting the spherical engaging part of the first closing unit, and the spherical engaging part of the first closing unit is held in a closed position of the closing device for the closing of the closing device in the cut out of the second closing unit, wherein - a sliding unit is located in the cut out (304, 304A) of the second closing unit, said sliding unit being preloaded in the direction of the opening of the cut out (304, 304A) of the second closing unit, wherein the sliding unit can be moved into an open position and a closed position along the wall (303, 307A) of the cut out (304, 304A) of the second closing unit in the cut out (304, 304A) of the second closing unit, - in the open position of the sliding unit, the spherical engaging part of the first closing unit can be received in the cut out (304, 304A) of the second closing unit through the opening of the cut out (304, 304A) of the second closing unit, - in the closed position of the sliding unit, the sliding unit delimits an extension of the cut out (304, 304A) of the second closing unit, - in the closed position of the sliding unit and in the closed position of the closing device, the spherical engaging part of the first closing unit lies against both the wall (303, 307A) of the cut out (304, 304A) of the second closing unit and against the sliding unit and is held clamped between the wall (303, 307A) of the cut out (304, 304A) of the second closing unit and the sliding unit, - the spherical engaging part of the first closing unit is magnetic, - a magnetic unit is arranged in the cut out (304, 304A), which interacts with the magnetically formed engaging part of the first closing unit, - the magnetic unit comprises a first outer side and a second outer side, - the first outer side is oriented toward the opening of the cut out (304, 304A), - the second outer side is situated opposite the first outer side, - in the closed position of the sliding unit, the sliding unit is arranged at the second outer side, - the sliding unit has a prolongation, which extends along a side surface of the magnetic unit in the direction of the opening of the cut out (304, 304A), and wherein - the second closing unit comprises a wall cut out, in which the magnetic unit is arranged.