If you would escape moral and physical assassination, do nothing, say nothing, be nothing — court obscurity, for only in oblivion does safety lie.

Elbert Hubbard (1856-1915) American writer, businessman, philosopher

Little Journeys to the Homes of American Statemen, “William H. Seward” (1916)
    (Source)

Variants show up elsewhere in Hubbard's writings and and his quote epigrams.

• To escape criticism -- do nothing, say nothing, be nothing.
• To avoid unkind criticism: do nothing, say nothing, be nothing.
• There is only one way to avoid criticism: do nothing, say nothing and be nothing.

Often misattributed to Aristotle.