What is not allowed when a player mistakenly plays a ball out of bounds?

When a player mistakenly plays a ball out of bounds, they may not play the ball if it is out of bounds because the Rules of Golf state that a ball that goes out of bounds is considered to be lost. This means that the player must take a penalty stroke and play another ball from the nearest point of reference, which is typically the location where the previous stroke was taken, but it cannot include the out of bounds ball itself. The rule essentially reinforces that if a ball is deemed out of bounds, it cannot be played again, thereby allowing for a fresh start without further penalty on the out-of-bounds ball.

According to the rules, if a ball is out of bounds, the player must return to the original spot to hit a new ball, but they must do so with the understanding that the original ball is no longer in play. The emphasis on the ball being out of bounds ensures that players understand the importance of hitting a valid shot from a permissible area on the course, aligning with the overall objective of maintaining fair play.