It's the heart of a pig you hold in your hand.
10 seconds sound clip from the Snow White and the Seven Dwarfs (1938) classic radio play.
You can hear this line at 00:35:54 in the radio play.
Quote context
[...]
- Magic mirror on the wall, who now is the fairest one of all?
- Snow White lies dead in the forest. The Huntsman has brought me proof. Behold, her heart.
- Snow White still lives, the fairest in the land.
- It's the heart of a pig you hold in your hand.
- The heart of a pig? Then I've been tricked! The heart of a pig! The blundering fool!
- I'll go myself to the dwarfs' cottage in a disguise so complete no one will ever suspect.
- I'll transform my beauty into ugliness. Change my queenly raiment to a peddler's cloak.
- To shroud my clothes, the black of night.
[...]