“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.”
Matthew 12:40 — Greek Interlinear
Church Fathers on Matthew 12:40
Because the Lord had so oft repressed the shameless tongue of the Pharisees by His sayings, they now turn to His works, whereat the Evangelist wondering, says, 'Then certain of the Scribes and Pharisees answered, saying, Master, we would see a sign of thee;' and that at a time when they should have been moved, when they should have wondered, and been dumb with astonishment; yet even at such time they desist not from their malice. For they say, 'We would see a sign of thee,'…
They require a sign of Him, as though what they had seen were not signs; and in another Evangelist what they required is more fully expressed, 'We would see of thee a sign from heaven.'
Then He begins to answer them, giving them a sign not from heaven, which they were unworthy to see, but giving it them from the deep beneath. But to His own disciples He gave a sign from heaven, to whom He shewed the glory of His blessed eternity both in a figure on the mount, and after in verity when He was taken up into heaven.