A fitting for a pipe, has a base body and a connecting body, each having a passage for a fluid. Both bodies include contact surfaces that can be slid into each other, including at least one pair of opposing recesses forming a receiving chamber. The fitting has a flexible, substantially incompressible locking element that can be inserted into the receiving chamber for fixing the two bodies together. At least one of the two bodies includes an access chamber extending between an outer surface of the associated body and the receiving chamber. The access chamber connects to and is an extension of the receiving chamber. The locking element includes a stop protrusion at one of its opposite ends for stopping the locking element externally at least one of the two bodies in order to prevent the locking element from unintentionally slipping out of the receiving chamber.