When the Pharisees asked for a sign, the Lord Jesus said in Matthew:
12:38 Then certain of the scribes and of the Pharisees answered, saying, Master, we would see a sign from thee.
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 to it, but the sign of the prophet Jonas:
12:40 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.
Why then the scribes and Pharisees did not say anything about what the Lord said? I mean, did they understand that the Lord will die and come back after 3 days? Did they not know that Jonah died inside the belly of fish and was raised back?
The Scribes and Pharisees were highly trained and knowledgeable students of the Bible. That was not the problem. The problem was that they considered Jesus to be just a man, and an uneducated one at that. Although He had fulfilled some of the prophecies about the Messiah, He hadn’t fulfilled any of the ones they were looking for.
He wasn’t a powerful King with a great army that would defeat the Romans and make them free again. He wasn’t from a prominent family. Almost none of the experts of the day confirmed His Messianic claims. His followers were largely poor, ignorant common folk who would never amount to anything.
But after His Resurrection they remembered His promise and changed their minds about Him. Of the 3000 who became Christians on the Day of Pentecost, many were Pharisees.