Dragon Ball Z - episode 79 - 19 Feb, 1991

Having transformed into a larger state and gaining much more power, Frieza has mortally wounded Krillin with his left horn, and flings him into the Namekian sea. After seeing his friend attacked, Gohan tries to save him but Frieza blocks the young Saiyan, intending to let the Earthling die in his watery grave. Enraged, Gohan suddenly loses control of himself and unleashes a furious attack on Frieza, blasting him into the ground. Though he becomes powerful out of anger, his Masenko is not strong enough to kill Frieza, who gets up and powers up again for the second time. While Dende pulls the injured but still-living Krillin out of the water, Frieza pounds the inexperienced Gohan. Vegeta then unleashes an attack on Frieza with his full power, but Frieza is completely unfazed. (Source: Wikipedia)