Dragon Ball Z - episode 96 - 25 Jun, 1991

Much to Frieza's horror, Goku has finally become a Super Saiyan, surrounded by a gold aura, the fuel of this power being his anger towards Frieza. As Gohan takes Piccolo to Goku's ship, the hero starts to pound on Frieza as the tyrant fires back, but none of his attacks work against Goku, now that he is a Super Saiyan. (Source: Wikipedia)