I can't count the number of times I've heard that Pascal quote about there being a God-shaped vacuum in our hearts. A friend once asked me where Pascal said it, and I said I didn't know. I'd never really spent any time reading Pascal. He assured that it was somewhere in the Pensees, but he wanted to know exactly where. I couldn't really help him. The problem is that no one could help him. Pascal never said any such thing. Douglas Groothuis provides a quote that does say something in the remote ballpark:
What else does this craving, and this helplessness, proclaim but that there was once in man a true happiness, of which all that now remains is the empty print and trace? This he tries in vain to fill with everything around him, seeking in things that are not there the help he cannot find in those that are, though none can help, since this infinite abyss can be filled only with an infinite and immutable object; in other words by God himself. [Pascal, Pensees #425]
Whenever anyone gives you a quote without providing a reference, assume the quote has been misattributed. If the reference includes a book but nothing more specific, always assume the quote has been misattributed before spreading on what might be completely false. People who can't cite page numbers (or section locations for older works) probably shouldn't be trusted. It's likely that, as in this case, the reality is much better than the legend. What Pascal really said is much more eloquent than what the urban legend says he said.