DB Chapter 343
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
"Vegeta Returns!!!" (ベジータ出現, Bejīta Shutsugen; Literally meaning "Vegeta Makes His Appearance") is chapter 343 of the Dragon Ball manga.
Everyone is shocked to see Vegeta, and Piccolo says that Vegeta got in the way to keep him from helping Goku earlier; there's no way an attack of that caliber could've defeated him. Vegeta says he saw everything. He tells Kakarrot he's stupid for turning Super Saiyan even though he knew his body was in danger. It only sped up the heart disease's effects. He then tells Kakarrot his objective will be him (Kakarrot) to the end, and kicks Goku across the ground. Piccolo catches him. Vegeta tells someone to take him home and give him his medicine. Gohan volunteers, but then Yamcha steps in. Yamcha regretfully says he probably wouldn't be much help here. Piccolo says it's like a virus, so Yamcha might want to take some medicine too in case it spreads. Then Yamcha flies off with Goku over his shoulder.
No. 20 tells No. 19 that he doesn't have to follow them, for now these noisy flies need to be taken care of. It's gotten interesting with the addition of Vegeta. Kuririn then wonders, "Wouldn't it be good if we had an hour-long break? I mean... The guy from the future said without Goku, all of us, even Vegeta, get killed. The circumstances are a bit different, but isn't it still pretty much the same?" Gohan says if they run away, they'll just do like what they did to that city. Kuririn realizes they'll have to hold on until Goku gets healed, but Piccolo says it's not confined to what that boy said, since the time Goku's disease surfaced was considerably off. Piccolo figures his coming back in time may have subtly changed history. No. 19 asks if he can take care of Vegeta. No. 20 thinks he's being greedy after all the energy he absorbed from Goku, but gives him the okay. No. 20 decides to take care of the other four though. Vegeta says he's been watching everything, and knows how they absorb energy from the palm of their hands, so he'll just have to be sure and avoid that.
No. 19 says Vegeta may have seen the situation, but he hasn't heard the details — they already know all of Vegeta's fighting techniques. Vegeta says they looked really surprised to see Kakarrot as a Super Saiyan, so he figures their data doesn't include anything from the fight with Freeza up to the present. Then he wants to know if artificial humans feel fear, and then suddenly transforms into a Super Saiyan, and everyone is shocked. Kuririn had thought you needed a calm heart to become a Super Saiyan. "My heart was calm... Calm and pure... Pure evil, that is... I wished for nothing but to get strong... And so, I repeatedly trained intensely... Then, I realized my own limits... With my anger at myself, I suddenly awoke...as a Super Saiyan!!! I was overcome with joy... At last, the time has come when I have returned to being the Saiyan prince who has surpassed Kakarrot..."
No. 20 thinks he'll just end up like Son Goku did, and No. 19 chuckles, then charges at Vegeta. He hits Vegeta in the face with a hard punch, knocking Vegeta back a bit, but not off his feet. "So that's your level... I didn't mention it, but... When I become a Super Saiyan, I grow even more brutal... And I get a little excited... You don't feel pain, do you? How lucky." Vegeta kicks No. 19 in the stomach, elbows him in the face, and then kicks him across the ground.