George Bernard Shaw is said to have told W.S.C.:
Am reserving two tickets for you for my premiere. Come and bring a friend—if you have one.
W.S.C. to G.B.S.:
Impossible to be present for the first performance. Will attend the second—if there is one.
Notes from Wikiquote
Apocryphal, from 1946. See discussion at Winston Churchill#Misattributed, and detailed discussion at "Here are Two Tickets for the Opening of My Play. Bring a Friend—If You Have One", Garson O'Toole, Quote Investigator, (March 25, 2012)