Railing post (10.1, 10.2, 10.3) for scaffolding having scaffolding levels (52, 54) with vertical members (58.1, 58.2)/vertical frames running in a longitudinal direction /vertical direction, with crossbars (60.1, 60.2) running in a transverse direction /horizontal direction, guard rails and decks, for the mounting of a so-called leading railing, by means of which at least one temporary, telescopic guard rail can be mounted, from an existing lower scaffolding level, for an upper scaffolding level to be mounted thereabove, with - a first connection device (12.1, 12.2), - a second connection device, - a third connection device, wherein - the first connection device (12.1, 12.2) is arranged in the upper end region of the railing post (10.1, 10.2, 10.3), to which at least one temporary guard rail can be releasably connected, - the third connection unit is arranged in the lower end region of the scaffolding post (10.1, 10.2, 10.3), which can be releasably connected to existing components of the scaffolding, in particular to the vertical member (58.1) with connected guard rails or a rosette of the vertical member (58.2), - the second connection device is arranged at a distance in the longitudinal direction above the third connection device, which can be connected to the vertical member (58.1, 58.2) of the scaffolding in a releasably lockable manner, - a continuous rotatable shaft is arranged within the railing post (10.1, 10.2, 10.3), - the rotatable shaft is connected to rotation actuation devices (22.1, 22.2), which are accessible from the outside and which are arranged in the upper and/or lower end region of the railing post (10.1, 10.2) and are rotatable in a direction of rotation, - the second connection device has a first form-fit unit connected fixedly to the railing post (10.1, 10.2, 10.3) and a rotatable form-fit unit connected above or below or within the fixed form-fit unit, which rotatable form-fit unit is movable from a closed position to a maximum opening position, and vice versa, wherein in the closed position a positive locking of an inserted railing post (10.1, 10.2, 10.3) on a vertical member (58.1, 58.2) of the scaffolding is obtained, - characterized in that - the rotatable form-fit unit is connected directly to the rotatable shaft so as to be rotatable about the longitudinal axis of the railing post (10.1, 10.2, 10.3), - an elastic element is present which acts on the movable form-fit unit and holds the latter in the closed position under its action alone, - the rotatable form-fit unit is designed in its front end region in such a way that, when it is pressed against a vertical member (58.1, 58.2) of the scaffolding, it initially opens in the opening direction and, after a predeterminable position/displacement of the vertical member (58.1, 58.2) is exceeded, that is to say when the maximum opening position is reached, it moves into the closed position due to the action of the spring force of the elastic element, and thus at least partially encloses the vertical member (58.1, 58.2) in a form-fitting manner and securely locks it. - a first connection device (12.1, 12.2), - a second connection device, - a third connection device, - the first connection device (12.1, 12.2) is arranged in the upper end region of the railing post (10.1, 10.2, 10.3), to which at least one temporary guard rail can be releasably connected, - the third connection unit is arranged in the lower end region of the scaffolding post (10.1, 10.2, 10.3), which can be releasably connected to existing components of the scaffolding, in particular to the vertical member (58.1) with connected guard rails or a rosette of the vertical member (58.2), - the second connection device is arranged at a distance in the longitudinal direction above the third connection device, which can be connected to the vertical member (58.1, 58.2) of the scaffolding in a releasably lockable manner, - a continuous rotatable shaft is arranged within the railing post (10.1, 10.2, 10.3), - the rotatable shaft is connected to rotation actuation devices (22.1, 22.2), which are accessible from the outside and which are arranged in the upper and/or lower end region of the railing post (10.1, 10.2) and are rotatable in a direction of rotation, - the second connection device has a first form-fit unit connected fixedly to the railing post (10.1, 10.2, 10.3) and a rotatable form-fit unit connected above or below or within the fixed form-fit unit, which rotatable form-fit unit is movable from a closed position to a maximum opening position, and vice versa, wherein in the closed position a positive locking of an inserted railing post (10.1, 10.2, 10.3) on a vertical member (58.1, 58.2) of the scaffolding is obtained, - characterized in that - the rotatable form-fit unit is connected directly to the rotatable shaft so as to be rotatable about the longitudinal axis of the railing post (10.1, 10.2, 10.3), - an elastic element is present which acts on the movable form-fit unit and holds the latter in the closed position under its action alone, - the rotatable form-fit unit is designed in its front end region in such a way that, when it is pressed against a vertical member (58.1, 58.2) of the scaffolding, it initially opens in the opening direction and, after a predeterminable position/displacement of the vertical member (58.1, 58.2) is exceeded, that is to say when the maximum opening position is reached, it moves into the closed position due to the action of the spring force of the elastic element, and thus at least partially encloses the vertical member (58.1, 58.2) in a form-fitting manner and securely locks it.