The Demon in the Snow

is episode 19 of the original Naruto anime.

Synopsis
Gatō, with his men, plans to kill Zabuza. He told Kakashi that their fight is over to which he agreed. Naruto got angry when Gatō stepped onto Haku's dead body. Zabuza said that he only uses Haku. Naruto finally convinces Zabuza saying that Haku loved him and so help him fulfil his dreams. Finally, Zabuza appreciates Haku's sacrifice and broke his heart in fighting them, and happy to fight them as his final opponents. Zabuza borrowed Naruto's kunai to prepare to take his revenge on Gatō, wielding a kunai on his mouth since his arms were broken by Kakashi, but before he could get near to Gatō, he was stabbed multiple times by his men. However, he still managed to kill the latter even with his sever injuries.

Sasuke was alive, which Sakura and Naruto became happy. The men were scared away thanks to the villagers, Naruto and Kakashi's (fooling them) efforts. The dying Zabuza requested Kakashi to bring him beside Haku. He said that he wants to go to the same place as him. Kakashi said that he can go there also.

The team buried them and placed Zabuza's sword, Kubikiribōchō near his grave. Naruto, saying he wants to have his own ninja way. He bids goodbye to Inari, as Team 7 departs to Konoha. They discover that Tazuna named the bridge the Great Naruto Bridge.

Trivia

 * In the manga, when attacking Gatō, Zabuza cuts his head off, rather than slashing him up and pushing him into the sea.