When Ralph stops the ball for his mate, Ralph it is most likely because he is saving Dave’s ball from being possibly lost or irretrievable from the Hazard.
Or he could just have been saving the ball for his mate and Dave plays it as entering the hazard, takes his drop, plays on, and says thanks to Ralph for saving his ball from drowning?
That is a real situation. I have seen it happen. It was a long time ago, not at my current Course. At the other Club a par 5 has a typical third stroke over a dam from usually a downhill lie. There is a bunker running the full length of the green, behind the green.
As you would expect play from the bunker has a good fear factor and if the bunker shot is caught thin the dam will be a likely place for the Ball to finish.
At that time I was not familiar with the Rules, had no idea what might apply . I think the bloke whose ball was stopped thanked his mate and wiped the hole.
My new course does not have a bunker behind but the scenario I put in the original post is similar except for the bunker. It is a par 3.