In Jersey City, within hours of two jetliners' plowing into the World Trade Center, law enforcement authorities detained and questioned a number of people who were allegedly seen celebrating the attacks and holding tailgate-style parties on rooftops while they watched the devastation on the other side of the river.That's not exactly comprehensive proof of Trump's "thousands and thousands" claim.
Thousands and thousands of Muslims WERE celebrating on 911, seen all over the country and widely reported, even in New Jersey. I remember seeing it myself. I've also seen large numbers of testimony from people actually from New Jersey saying it was well known that Muslims were celebrating the terror attacks-- not just a few people here or there, but people claiming to have seen large numbers of people in independent accounts. I even read an article recently that said the Police department over there had countless numbers of reports about Muslims celebrating in New Jersey.
I guess you might say there's no way to quantify it as being "thousands," but to resist the inevitable truth here that there was wide spread celebrations is futile.
Even now, threads on this have prompted several Freepers to begin recounting their recollections.
That article is A source.
It is not and never was THE source.