Goku is tasked with retrieving the from Master Roshi to extinguish the mountain's eternal flames.
The content for varies depending on which series in the franchise you are referring to. The most common "Episode 7" refers to the original 1986 series. Dragon Ball (Original Series) Episode 7 Dub Title: " The Ox-King on Fire Mountain " Dragon Ball (Dub) Episode 7
Vegeta, Piccolo, and Bulma arrive in the Demon Realm; Shin uses a spell to free Panzy from her tracking collar. "Universe Mission 7" Goku is tasked with retrieving the from Master