How could asking for a sign from Jesus tempt him?

Why did Jesus sigh deeply in his spirit (v12)? What was Jesus trying to say about the Pharisees in his response made in Matt 16:2-3?

Why did Jesus know that even if the Pharisees saw him perform a sign, they still would not believe him? (John 10:24-26)

What does the sign of Jonah (Matt 16:4) refer to? What is the genuine meaning of the sign to mankind?

Is there any correlation between seeking sign out of curiosity and believing in Jesus? What is the problem with it? (I Cor 1:21-24)

On whom did Jesus usually perform miracles? What was the purpose of those miracles?