There was only one sign Jesus gave to the Pharisees of His day that He is who He claimed to be. Since this was to be the only sign, it needs to be scrutinised to see if it stands or fails the test. The only place we can go to find out how the Pharisees were testing Jesus is in the bible. And it was recorded in Mat 12:38-42, along with the amazing response Jesus gave them.
What is the most important question you can ask when you are trying to prove the resurrection from the dead of our Lord and Saviour Jesus Christ? It is, how can I prove Jesus Christ was actually in the tomb for the exact amount of time he claimed he was going to be there? How important is it that he was in the tomb for exactly three days and three nights?
Only One Sign To Prove His Deity.