Kakashi and Orochimaru: Face-to-Face!

is episode 40 of the original Naruto anime.

Synopsis
Kakashi threatened to kill Orochimaru, a threat that Orochimaru took lightly. Despite this, Orochimaru chose to walk away. As he left, Kakashi admitted to himself that he could not have killed Orochimaru on his own. Meanwhile, Shino and Zaku Abumi continued their match; although Zaku revealed that he was in fact able to use both of his arms again, Shino ultimately won his match through the deceptive use of his destructive bugs, leaving Kankuro and Misumi Tsurugi to fight next.