Matthew 12:36-40

Mat 12:36 (KJB)
But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment.

Idle - Careless or useless

Jesus now tells these Pharisees that the words which they are speaking now will cause them to give account in the day of judgment. The Pharisees have the upper hand now but whatever they are preaching will have to be explained at the judgment seat of Christ before they are sentenced. The fact is that the idle words which they were speaking came from a darkened heart of sin. It meant that they were unsaved and enemies of Christ. There will come a time when the playing field will be level and they must give account of the meanings of what they were preaching. This is also a general principle not only applicable to the Pharisees. Every unsaved person will be required to give account of the words they speak at the Judgment Seat of Christ. Think of all those who will give account, comedians, politicians, demagogues, false preachers, or anyone who is unsaved. Those who think they are funny by swearing God’s name in vain or mocking the Lord Jesus Christ will give an account of their words on judgment day. This is in conjunction with the works that are performed also. So both words and works will be judged.

Mat 12:37 (KJB)
For by thy words thou shalt be justified, and by thy words thou shalt be condemned.

When the books are opened and the enemies of Christ appear before Him on Judgment Day, the words which they spoke on earth concerning the Lord Jesus Christ and the Gospel will condemn the unsaved. Since the words are already spoken, their fate will have been determined upon the moment of death. Unless they became saved, they will have to answer for every word they spoke against Christ and the true Gospel. The only way they would be justified is if they were saved and speaking the truth about Christ and the Gospel. (John 5:24 KJV) Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life. Those who have become saved will never come under judgment nor condemnation because all sins, both past and future have been removed from the believer and that is why we inherit eternal life the moment we become saved.

Mat 12:38 (KJB)
Then certain of the scribes and of the Pharisees answered, saying, Master, we would see a sign from thee.

Sign - Portent, miracle, or token

This is the first of five occasions where Jesus was asked to perform a sign. These scribes and Pharisees had quickly changed the subject. They did not believe Jesus unless He could verify who He was by means of doing some type of divine sign to convince them. If these scribes and Pharisees were following the ministry of Jesus, they would have seen the many miracles that He did. He did not do miracles for the purpose of an exhibition or to satisfy the curiosity of unbelievers. He did miracles for those who truly needed one and who showed faith toward Him.

Mat 12:39 (KJB)
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:

The essence of living the Christian life is to live it by faith and the opposite of that is to live by sight. (2 Cor 5:7 KJV) (For we walk by faith, not by sight:) It is not that a sign is something sinful as in the past God had done this, Gideon’s fleece, Ahaz in Isaiah 7, or Hezekiah in 2 Kings 20. Jesus here was speaking directly to the unrepentant Jews of that day who disbelieved the ministry of Christ and opposed Him. They did not even recognize any of the signs and miracles that He had done previously because they had walked away from God and created their own system of beliefs via their writings. Jesus was not willing to give them a sign at that particular time but they will get the sign they are looking for by means of looking at the prophet Jonah. They would have been familiar with the prophet Jonah but they would have to study it to see what the sign might be so they could recognize it when it happens.

Mat 12:40 (KJB)
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.

Jesus gives them the particulars of the comparison the Pharisees must make concerning the time Jonah was in the whale’s belly. They knew the time period of Jonah’s ordeal but they would have to make the comparison to some sign the Lord is going to show them in the future. Now some have stumbled at this verse believing that Christ was crucified on Wednesday so this way you could have three days and three nights. Where we get confused is that we are applying western thought to an eastern event. The Jews had commonly stated three days and not three 24 hour periods. So Sunday would have been the third day or three days Friday, Saturday, Sunday. It could also point to the fact that on Thursday in the Garden of Gethsemane, Jesus was sweating drops of blood which could identify with the fact that His suffering had begun in the Garden thus giving three full days and nights in the heart of the earth. The sign the Pharisees would be given was akin to the time frame of Jonah. As Jonah came out of the whale’s belly on the third day, Jesus would come out of the tomb on the third day and that was the only sign they would receive.