Ben Bernanke served as the chairman of the Federal Reserve from 2006 to 2014. He famously told Congress the Fed was absolutely not monetizing the debt in 2008. He said the difference between debt monetization and the Fed's policy was that the central bank was not providing a permanent source of financing. He said the Treasurys would only remain on the Fed's balance sheet temporarily. He was obviously wildly mistaken or outright lying.
In this clip from his podcast, Peter Schiff wonders out loud if Bernanke has ever told the truth.
Bernanke recently did an interview and the interviewer played clips of some of the things Bernanke said back in the run-up to the 2008 financial crisis, specifically about the problems in the subprime mortgage market being transitory and of no real threat to the broader economy.