Set of panels comprising a locking device

A set of panels comprising a first panel and a second panel and a locking device for locking a first edge portion of the first panel to a second edge portion of the second panel, wherein the first and second panels comprise a front side and a rear side, a normal of a main plane extending along the front and/or the rear side defining a vertical direction extending away from the front sides of the first and second panels, wherein the locking device comprises a horizontal locking device and a vertical locking device, the vertical locking device comprising:

• a separate tongue arranged in an insertion groove of said first edge portion, a longitudinal extension of the separate tongue extending along the first edge portion, and
• a tongue groove provided in, and extending along, said second edge portion, wherein in a vertically locked state of the first and second edge portions:
• an abutment member provided at a longitudinal end portion of the separate tongue cooperates with a stop surface of the second edge portion, the stop surface being planar and extending essentially vertically, and
• a locking portion of the separate tongue cooperates with the tongue groove,
• wherein, during locking, the locking portion is configured to be gradually inserted into the insertion groove along the first edge portion in a first stage, and in a second subsequent stage the locking portion is configured to be gradually inserted into the tongue groove along the second edge portion.