The March 12, 2013 Senate Intelligence Committee hearing in which Senator Ron Wyden asked Director of National Intelligence James Clapper whether the NSA collects data on millions of Americans. Three months later, the Snowden documents showed bulk collection of Americans' phone records.
Wyden: "does the NSA collect any type of data at all on millions, or hundreds of millions, of Americans?" Clapper: "Not wittingly. There are cases where they could inadvertently, perhaps, collect, but not wittingly."
pp. 66-67