For just as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth (Matthew 12:40).
Many people desire a tangible experience to validate their spiritual life. Some people call it "putting out a fleece." Other people say that God gave them a sign, or that they want God to give them a sign. We can appreciate how some might desire a sign even right now. God give me a sign that I will get through this difficult time and be alright.
However, God says that we have something better: "the more sure word of prophecy." We have God's complete revelation--the Bible. We also have the ultimate sign--the sign of Jonah--the resurrection of Christ. In Matthew 16:1-4 the Bible says:
And the Pharisees and Sadducees came, and to test Him they asked Him to show them a sign from heaven. 2 He answered them, "When it is evening, you say, "It will be fair weather, for the sky is red. 3 And in the morning, "it will be stormy today, for the sky is red and threatening." You know how to interpret the appearance of the sky, but you cannot interpret the signs of the times. 4 An evil and adulterous generation seeks for a sign, but no sign will be given to it except the sign of Jonah."
Earlier I shared the clarifying passage in Matthew 12. There Jesus makes clear that the sign of Jonah is His own resurrection. Jonah was in the whale for three days and then returned to land. Jesus was dead in the ground for three days and then returned to life. God has determined the only sign we need to believe Him is the empty tomb. Because Jesus rose from the dead, we know that God is in control. Because of the resurrection, we know that our good future is secured with Christ in heaven. Because of the empty tomb, we know that whatever we may experience in this life cannot be compared to the greater glory in the next life. Because of the sign of Jonah, we can trust God.