Khabib Nurmagomedov is currently preparing for the biggest fight of his life at UFC 209 on March, 4th of this year against Tony Ferguson. There has recently been a video released where Nurmagomedov actually repeatedly hits his sparring partner as hard as he can.
Nurmagomedov is not famous for his punching power, but his punches on the ground are brutal and his control on the ground is simply unmatched by any UFC fighter. He is so good on the ground that he was actually asking Dana White for a shot against Conor McGregor while Nurmagomedov was beating up Michael Johnson (who is actually a really good wrestler).
On the next page, it features the video where Khabib Nurmagomedov is actually throwing shots at his sparring partner with full force. It takes a very brave man to be able to take punches from Nurmagomedov. Russia is definitely a tough place when it comes to training.
(click on the page #2 tab below to see Nurmagomedov throw full-force strikes at his sparring partner)