The invention pertains to a nut and ferrule assembly for use in joining tubing to a fitting. The ferrule has a male member which interlocks with a nut and freely rotates within the nut. The interlock reduces the number of parts necessary to be handled, eliminates the need for the nut to be of the same material as the ferrule, reduces the possibility of flow restriction or tubing deformation associated with rotation of the ferrule, and aids in the removal of the ferrule from the detail when removal is desired.