Ask not what you can do for your potato

For years, many in the US and in Lebanon have maintained that JFK's statement, "Ask not what you can do for your country etc" is taken from a saying by Kahlil Gibran (or Jubran Khalil Jubran as we know him in Arabic).  And I have argued for years that it is not true and that Jubran never said that. The closest is an essay by Gibran titled (The New Era) in his book Al-Bada'i` wa-l-Tara'if and has this (my translation):  "A politician who says to himself: "I wish to benefit form my nation"? or an enthusiastic passionate person who whispers to himself: "I seek to benefit my nation"? (p. 101)