Matthew 12

Verse 38 - Then certain of the scribes and of the Pharisees answered, saying,
Master, we would see a sign from thee.

Verse 39 - But he answered and said unto them,
An evil and adulterous generation seeketh after a sign;
and there shall no sign be given to it, but the sign of the prophet Jonas:

Verse 40 - For as Jonas was Three Days AND Three Nights in the whale's belly;
so shall the Son of man be Three Days AND Three Nights in the heart of the earth.

King James Version