Saint Duffer rule no. 4:
In or near a bunker or sandtrap, a ball rolling back toward the player may be hit again on the roll without counting an extra stroke or strokes.
In any case, no more than two strokes are to be counted in playing from a bunker, since it is reasonable to assume that if the player had time to concentrate on his shot,instead of hurrying it so as not to delay his playing partners, he would be out in two.