Rule 4-4 of Rules of Golf

Question
Playing in a singles competition on the 18th hole, my co-player is in a greenside bunker and I'm on the green. He discovers that he has lost his sandwedge. Because I will not be using my sandwedge again can he borrow mine? If this happens on any other hole on the course can my co-player borrow any one of my clubs provided I agree not to use that club again?

Answer
Jack,

The following is from the USGA web site.

b. Partners May Share Clubs

Partners may share clubs, provided that the total number of clubs carried by the Partners so sharing does not exceed 14.

Only partners may share clubs as stated above.

Thanks for the question,

Michael