Albert Barnes Commentary Matthew 12:39

"But he answered and said unto them, An evil and adulterous generation seeketh after a sign; and there shall no sign be given it but the sign of Jonah the prophet:" — Matthew 12:39 (ASV)

An evil and adulterous generation. The relationship of the Jews to God was often represented as a marriage contract—God as the husband, and the Jewish people as the wife. (Hosea 3:1; Ezekiel 16:15). Hence, their apostasy and idolatry are often represented as adultery. This is probably the meaning here. They were evil and unfaithful to the covenant or to the commandments of God—an apostate and corrupt people. There is, however, evidence that they were literally an adulterous people.

There shall no sign be given to it. They sought some direct miracle from heaven. He replied that no such miracle would be given. He did not mean to say that He would work no more miracles or give no more evidence that He was the Christ; but He would give no such miracle as they required.

He would give one that ought to be as satisfactory evidence to them that He was from God, as the miraculous preservation of Jonah was to the Ninevites that he was divinely commissioned. As Jonah was preserved three days by miracle, and then restored alive, so He would be raised from the dead after three days. As on the ground of this preservation the Ninevites believed Jonah and repented, so on the ground of His resurrection the men of an adulterous and wicked generation ought to repent and believe that He was from God.

The sign of the prophet Jonas means the sign or evidence which was given to the people of Nineveh that he was from God—namely, that he had been miraculously preserved and was therefore divinely commissioned. The word Jonas is the Greek way of writing the Hebrew word Jonah, as Elias is for Elijah.