But when the knife pierced the heart of the portrait an extraordinary thing happened.

5 seconds sound clip from the The Picture of Dorian Gray movie soundboard.

You can hear this line at 01:47:01.835 in the Blu-ray version of the movie.

Quote context

[...]

- He would expel every sign of evil from the painted face. He would watch the hideousness fade and change.

- But the painting would always be there to tempt his weakness. Better to destroy it to grow old inevitably as all men grow old.

- If he fell into evil ways, to be punished as all men are punished.

- Better if each sin of his life were to bring its sure, swift penalty.

- The knife that had killed Basil Hallward would kill his portrait also and free him at a stroke from the evil enchantment of the past.

- But when the knife pierced the heart of the portrait an extraordinary thing happened.

- Pray, Father, forgive me. Pray, Father, forgive me for I have sinned. Pray, Father, forgive me for I have sinned. Through my fault, through my most grievous faults.

- Heaven forgive me.

- Take Gladys home, David.

[...]