The quote "You can fool some of the people some of the time, but not all of the people all the time" is a paraphrase of a line in Abraham Lincoln's 1858 speech given in Ottawa, Illinois, during his campaign for an Illinois Senate seat. The quote is often misattributed to Mark Twain.
This is what Abraham Lincoln actually said:
"You can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time."