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.