“It is not a pleasure for any President of the United States, as I am sure it was not a pleasure for my predecessors, to come before the Congress and ask for new appropriations which place burdens on our people. I came to this conclusion with some reluctance. But in my judgment, this is a most serious time in the life of our country and in the life of freedom around the globe, and it is the obligation, I believe, of the President of the United States to at least make his recommendations to the Members of the Congress, so that they can reach their own conclusions with that judgment before them. You must decide yourselves, as I have decided, and I am confident that whether you finally decide in the way that I have decided or not, that your judgment--as my judgment--is reached on what is in the best interests of our country.”

2010s, 2015, Presidential Bid Announcement (June 16, 2015)

2014, Young Southeast Asian Leaders Initiative Town Hall Speech (November 2014)
Context: I’m very proud of the United States. I believe that the United States is a force for good around the world. But I wouldn’t be a good President if I don’t listen to criticism of our policies and stay open to what other countries say about us. Sometimes I think those criticisms are unfair. Sometimes I think people like to complain about the United States because we’re doing too much. Sometimes they complain because they’re doing too little. Every problem around the world, why isn’t the United States doing something about it. Sometimes there are countries that don’t take responsibility for themselves and they want us to fix it. And then when we do try to fix it, they say why are you meddling in our affairs. Yes, it’s kind of frustrating sometimes. But the fact that we are getting these criticisms means that we’re constantly thinking, okay, is this how we should apply this policy? Are we doing the right thing when we provide aid to a country, but the country is still ruled by a small elite and maybe it’s not getting down to the people? Are we doing the right thing when we engage in training a military to become more professional, but maybe the military is still engaging in repressive activity? If we’re not open to those criticisms, then we won’t get better, we won’t improve.

To a temperance reformer.
Quoted in Gentleman Boss: The Life of Chester Alan Arthur, ch. 8, Thomas C. Reeves (1975).
1880s

"Remarks at the Cheney Stadium in Tacoma, Washington (387)" (27 September 1963) http://www.jfklibrary.org/Research/Research-Aids/Ready-Reference/JFK-Quotations.aspx
1963

2012, Yangon University Speech (November 2012)

1961, Berlin Crisis speech

A statement he is reported to have made several times to others after the secession of South Carolina, or as early as after the election of Abraham Lincoln (1860), as quoted in Lincoln's War: The Untold Story of America's Greatest President as Commander in Chief (2004) by Geoffrey Perret.

2010s, 2016, June, Speech about the Orlando Shooting (June 13, 2016)

As quote in D. F. Murphy, Presidential Election, 1864 https://books.google.com/books?id=_SAQAAAAYAAJ. Proceedings of the National Union Convention (June 7-8, 1864) of the Republican party