If a player's ball in motion accidentally hits any person or outside influence:
- There is no penalty to any player.
- This is true even if the ball hits the player, the opponent or any other player or any of their caddies or equipment.
Exception - Ball Played on Putting Green in Stroke Play: If the player's ball in motion hits another ball at rest on the putting green and both balls were on the putting green before the stroke, the player gets the general penalty (two penalty strokes).
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