Mr. Speaker, Mr. President, Members of the House, Members of the Senate, my fellow Americans:

All I have I would have given gladly not to be standing here today.

Lyndon B. Johnson (1908-1973) American politician, educator, US President (1963-69)

Speech (1963-11-27), “Let Us Continue,” Joint Session of Congress, Washington, D. C.
    (Source)

Five days after the assassination of John F. Kennedy.