For example, The Telegraph reported just this year that Sir Francis Buller ruled in 1886 that a man could beat his wife with a stick no thicker than his thumb, which thus created the popular, and sexist, idiom.
But way back in 1998, wordsmith William Safire told a different story in The New York Times. He cites "rule of thumb" as early as 1692 and then again, as an established proverb in 1721.
Buller did, however, make a similar comment much later in history. Someone should have knocked some sense into him — preferably with a stick much wider than a thumb.
Read more: https://www.businessinsider.com/offensive-phrases-that-people-still-use-2013-11#ixzz2kQ7XcuL5