Matthew 12:39
But He said to them, "It is [only] an evil and unfaithful [i.e., to God] generation of people that looks for a [supernatural] sign. And there will not be any sign given to it except the [supernatural] sign [demonstrated in the life] of Jonah, the prophet.
Matthew 16:4
"It is an evil and spiritually unfaithful generation of people [that keeps on] looking for a [supernatural] sign; but there will be no [such] sign given to it except the sign of Jonah [i.e., being in the huge fish for three days]." Then He left them and went away.
Luke 11:29-32
And when the crowds thronged around Jesus, He began saying, "This generation of people is evil, [for] it is looking for a [supernatural] sign. But no [such] sign will be given to it except the sign [demonstrated in the life] of Jonah.
Mark 8:38
For whoever will be ashamed of me and of my words in this [spiritually] unfaithful and sinful generation, the Son of man will also be ashamed of him when He returns in the splendor of His Father, accompanied by the holy angels."
James 4:4
You people who have become unfaithful to God, do you not know that being [intimate] friends with the world [of sin] means hostility toward God? Therefore, whoever determines to be an [intimate] friend of the world becomes an enemy of God.