That's one small step for a man, a giant leap for mankind
Neil Armstrong's words on first setting foot on the moon, in 1969. A strong contender as the most famous line ever to have been uttered.
Armstrong's words are sometimes given as, "That's one small step for man, one giant leap for mankind." Clearly the event was of huge significance and the choice of words was quite deliberate. Armstrong maintained for some time later that he said "for a man" rather than "for man". That line was what he, with the help of his wife, had prepared in advance. The rather fuzzy tapes of the event aren't clear enough to be sure, although the 'a' does appear to be missing.
In more recent years, after listening again to the recording, Armstrong has acknowledged that he may have fluffed his line. More recently still, analysis of the tape indicates that the 'a' may have be present on the recording but is too indistinct to hear.