A lock, such as a mortise lock, for a door. The lock comprises a locking cylinder that can be inserted into a door leaf and a shaft having two sections, each section of the shaft having a handle at the end, preferably a rotary knob or a standard door handle and being actively interconnected by a coupling after recognition of an authorisation code. The lock can be used for various applications as a result of its construction design, with a standard locking cylinder in various doors and that it allows, a simple, reliable, low-energy actuation of the locking mechanism. To achieve this, the coupling (11) comprises at least two, preferably four or more rolling members (17) that are guided in recesses (18) of a second part (10) of a first section (5) of the shaft (3). The rolling members can be pushed into cavities (20) that run around the periphery of the first part (9) of the first section (5) of the shaft (3), in order to actively connect a first part (9) and the second part (10) of the first section (5) of the shaft (3), using a radially or axially displaceable sliding element (22).
