picked and cleaned wrong ball

[simwood2]

One of my FC's by mistake marked, picked up and cleaned my ball on the fairway (whilst preferred lies where in operation) before I had got to where our two balls lay about 1 meter apart. I noticed before any shots were played and as it was just a knock i told him to just replace it and we could carry on, playing the correct balls from the correct spots. If it had been a comp, stroke play or match play what would have been the correct ruling?

 

[rulefan]

You were correct. Either you or he must replace the ball on its correct spot. No penalty.

It would have been different if it had been your partner (or opponent) when you (or opponent) would get a 1 stroke penalty.

See Rule 18
http://www.usga.org/Rule-Books/Rules-of-Golf/Rule-18/