DB Chapter 62
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
"The Ninja Split!" (危機！分身の術, Kiki! Bunshin no Jutsu; Literally meaning "Danger! The Art of Division") is chapter 062 of the Dragon Ball manga.
Goku is chasing Murasaki around outside again, but when they get near a lake Murasaki throws another smoke bomb at Goku. When the smoke clears, Murasaki is wearing snowshoe-looking things on his feet so he can walk across the water. This is his Amenbo no Jutsu (Water-walking Technique). Goku doesn't see what the big deal is, and Murasaki calls across from the other side that there's piranha in the lake. Goku says he's not limited to getting across by swimming, and he jumps all the way across to the other side. Murasaki asks if he's a frog, and Goku asks if they'll fight for real this time.
Murasaki starts whistling, and he announces his Bunshin no Jutsu (Art of Division). There are now five Murasaki's, and they've got Goku surrounded. Goku looks around, thinking they all look real, until one of them throws some kunai at him. Thinking he has found the real one, Goku runs after him, but then another Murasaki cuts in front of him with a katana. Goku prepares to attack him, when a third Murasaki starts firing at him with a revolver. Goku thinks they all look real, and one of the Murasaki's says it's because they are all real. They are quintuplet ninjas!
Goku gets it now, and the five of them come at him, intending to cut him up like raw fish. They all swing at him, but Goku uses Zanzōken, and they're only hitting an afterimage. The Murasaki's realize the brat can use real a "Art of Division". The real Goku whacks one of them in the head with Nyoi-Bō, then kicks another in the face, knocking them both out. Another one yells to be careful, while Goku knocks out the remaining two. The last Murasaki can't believe this, so he runs up to a higher part of the room. He comes to a cage, and yells inside at Artificial Human No. 8 to come beat up this brat. Goku catches up, and No. 8 looks big and scary.