Carleton, Barbee Oliver. Wonderful Cat of Cobbie Bean, The. 1967. Archive.org.

In Salem of witchcraft days, a large gray cat who says, "Magic, the world's full of it," teaches the ne'er-do-well Cobbie Bean the secret of happiness and success, and saves his life when Cobbie, the object of envy, is accused of witchcraft. Illustrated by Jacob Landau

I enjoyed her last book that I went to look for more of her books, and found this very short story. Quick read and a fun one to boot!