I hate writing. I love having written.

Dorothy Parker (1893-1967) American writer, poet, wit

(Spurious)

Not found in any of Parker's works, and not attributed to her until several years after her death. The earliest rendition of a thought like this ("Don't like to write, but like having written") comes from novelist Frank Norris in a posthumous letter published in "The Bellman's Book Plate: The Writing Grind," The Bellman (4 Dec 1915).

More discussion here: Don’t Like to Write, But Like Having Written – Quote Investigator.

See also Pratchett.