On 10th July 1925, the Zoroastrian guru Meher Baba shut up and didn't speak again until he died in 1969. He travelled widely and talked to Mahatma Gandhi, Maurice "Zank 'eaven for liddle girls" Chevalier, Timothy "LSD" Leary and Pete "The Who" Townshend. He communicated by signs and repeatedly promised his devotees and the press that he would speak at such a time and place but always felt that the time wasn't right as the moment approached. This was a pity because if he had spoken The Word, everything would have been clear for the next 700 years. Dang!
For a guy who didn't speak, he has accrued a long list of quotes, the most widely re-tweeted of which is "Don't worry, be happy", which inspired Bobby McFerrin. Many of his followers celebrate today by following his example and not speaking. Good idea, we're well into Ramadan at the moment where muslims are giving up more.