Other source:
As the battle continues, it seems neither warrior is going to win before Namek’s explosion. However, Goku soon notices that Frieza’s power is quickly decreasing, due to the protracted battle wearing him out. Eventually, Goku decides to call it quits and begins to depart towards his spaceship. Unable to accept this, Frieza launches a pair of heat-seeking energy disks at Goku. The Super Saiyan manages to avoid this, however, and eventually Frieza is sliced in half by his own attack.
