Matthew 12:40 Holman Christian Standard Bible (HCSB)
40 For as Jonah was in the belly of the huge fish three days and three nights, so the Son of Man will be in the heart of the earth three days and three nights.
Luke 11:29-30 Holman Christian Standard Bible (HCSB)
The Sign of Jonah
29 As the crowds were increasing, He began saying: “This generation is an evil generation. It demands a sign, but no sign will be given to it except the sign of Jonah.[a] 30 For just as Jonah became a sign to the people of Nineveh, so also the Son of Man will be to this generation.