That blast came from the Death Star. That thing's operational!
4 seconds sound clip from the Star Wars: Episode VI - Return of the Jedi movie soundboard.
You can hear this line at 01:42:00.941 in the Blu-ray version of the movie.
Quote context
[...]
- As you can see, my young apprentice, your friends have failed.
- Now witness the firepower of this fully armed and operational battle station.
- Fire.
- That blast came from the Death Star. That thing's operational!
- Home 1, this is Gold Leader.
- It's all right. All craft prepare to retreat.
- You won't get another chance at this, Admiral.
- We have no choice, General Calrissian. Our cruisers can't repel firepower of that magnitude.
- Han will have that shield down. We've got to give him more time.
[...]