The Oath of Pain

is episode 8 of the original Naruto anime.

Synopsis
With Kakashi having been captured in Zabuza's Water Prison Technique, Naruto, Sasuke, and Sakura were forced to defend against Zabuza's attacks. Kakashi told them to run, and Naruto became scared, wanting to flee, but he soon remembered his oath of pain. He had no other choice but to fight, so they could save Kakashi and keep Tazuna alive. Realising that he must work together with Sasuke to save Kakashi, Naruto used his Shadow Clone Technique, so all the clones jumped and completely surrounded Zabuza's clone. Then Zabuza's clone swung his sword, causing most of the clones to scatter and disappear. The last of the Naruto clones took a windmill shuriken (that Naruto had transformed into) and gave it to Sasuke. Then Sasuke used Shadow Shuriken Technique, the first shuriken being Sasuke's own shuriken and the second one being Naruto's. Naruto's shuriken was hidden underneath Sasuke's. Zabuza caught Sasuke's shuriken and dodged Naruto's. Naruto then transformed back into his original form and threw a kunai at Zabuza, forcing him to stop his jutsu, therefore freeing Kakashi.