Caddies (Rule 10.3)

Rule 10.3a allows a player to have one caddie at a time to carry their clubs and provide advice and other assistance. Having more than one caddie at a time is a breach; the penalty is two strokes (stroke play) or loss of hole (match play) for each...

Source: Rule 10.3, Rule 7.1, Rule 13.2, Rule 14.1, Rule 10.2

Send this to your friend — argument over.