3.11 PLAYER WISHING TO REJOIN THE MATCH

(a) A player who has an open or bleeding wound must leave the playing area. The player must not return until the bleeding is controlled and the wound has been covered.
(b) A player who leaves a match because of injury or any other reason must not rejoin the match until the referee permits the player to return. The referee must not let a player rejoin a match until the ball is dead.

(c) If a player rejoins or a replacement/substitute joins the match without the referee’s permission, and the referee believes the player did so to help that player’s team or obstruct the opposing team, the referee penalises the player for misconduct.
Sanction: A penalty kick is awarded at the place where play would restart.