“If there is anyone here whom I have not insulted, I beg his pardon.”
As quoted (prefaced by the qualification, "There is a story that one evening, on leaving, Brahms said...") in One Hundred Songs by Ten Masters: Volume II https://books.google.com/books?id=irUQAAAAYAAJ&pg=PR12 (1917), edited by Henry T. Finck, p. XII
Attributed
Varianta: If there is any one here tonight whom I have not offended, I apologize!