Hold your horses

Although grooms and riders have been holding or controlling horses for centuries, the figurative meaning of this expression as in to wait and be patient is generally thought to be of American origin from the mid-19th century. Eric Partridge, however, maintains the expression is British and was a common military command in the Royal Artillery during the 19th century. Whether of British or American origin, the original and literal horse-handling expression became figurative at some stage during the 19th century.