The saying has been attributed most often to Ben Franklin,who is also credited with having said,"By failing to prepare,you are preparing to fail.”
More recent variations,along with their attributions,include:
“Fail to plan,plan to fail.” Carl W.Buechner
“Failures don't plan to fail; they fail to plan.” Harvey MacKay
"He who fails to plan is planning to fail." Winston Churchill (during WW II)