9318807 - The rule itself explains this best here.
19-3. By Opponent, Caddie or Equipment in Match Play
If a player’s ball is accidentally deflected or stopped by an opponent, his caddie or his equipment, there is no penalty. The player may, before another stroke is made by either side, cancel the stroke and play a ball, without penalty, as nearly as possible at the spot from which the original ball was last played (Rule 20-5) or he may play the ball as it lies. However, if the player elects not to cancel the stroke and the ball has come to rest in or on the opponent’s or his caddie’s clothes or equipment, the ball must through the green or in a hazard be dropped, or on the putting green be placed, as near as possible to the spot directly under the place where the ball came to rest in or on the article, but not nearer the hole.