“Be happy, be happy; you shall have your red rose. I will build it out of music by moonlight, and stain it with my own heart's-blood. All that I ask of you in return is that you will be a true lover, for Love is wiser than Philosophy, though she is wise, and mightier than Power, though he is mighty.”

Source: The Nightingale and the Rose

The Golden Speech (1601)

Source: Dear John

John Tyree, Epilogue, p. 275
Source: 2000s, Dear John (2006)

Saying stated to his disciples

Source: Microserfs

Source: Prep

Source: Ocean Sea

Said to Abraham Lincoln on the ride back from Lincoln's inauguration as president (4 March 1861); as quoted in James Buchanan (2004) by Jean H. Baker, Pg 140; This or slightly paraphrased variants or abbreviated versions have also been been reported as having been said before the inauguration:
Sir, if you are as happy in entering the White House as I shall feel on returning [home], you are a happy man indeed.
If you are as happy entering the presidency as I am in leaving it, then you are truly a happy man.
As quoted in Presidential Leadership : Rating the Best and the Worst in the White House (2004) edited by James Taranto and Leonard Leo
Earlier variant: Some knave or fool got up a lie from the whole cloth and it was telegraphed over the country that I was about to purchase or had purchased a place somewhere else and would not return to Wheatland. If my successor should be as happy in entering the White House as I shall feel on returning to Wheatland he will indeed be a happy man. I am just now in my own mind chalking out the course of my last message. In it, should Providence continue his blessing, I shall have nothing to record but uninterrupted success for my country. The trouble about the slavery question would all have been avoided, had the Country submitted to the decision of the Supreme Court delivered two or three days after my inaugural.
Letter to William Carpenter (13 September 1860); as published in Historical Papers and Addresses of the Lancaster County Historical Society.