Jesus' own words (recorded in Matthew 12:40) attest without doubt that he would be buried (be in the heart of the earth) for 3 days and 3 nights. Mark 15:42,43 mention Jesus' death and burial on the day before a sabbath; John 20:1 (cp. also Matthew 28:1; Mark 16:2; Luke 24:1) mentions, that the grave was already empty on the first day of the week (Sunday). How can Jesus die and be buried on Friday and the grave be already empty on Sunday early morning when he was to be in the grave 3 days and 3 nights?
There is actually absolutely no contradiction between the verses mentioned above from the gospels. The contradiction is in this case really not in the Bible but between the biblical teaching and those doctrines which are taught traditionally about the day and time of Jesus' death and resurrection.
A correct understanding will be eminate from a careful consideration of the time references made in Scripture. Again and again there is mention made about the Feast of Passover or Feast of Unleavend Bread. From the records it is clearly seen that Jesus Christ died on the day before the beginning of this Feast (the preparation day). Since the first day of the Feast was a sabbath, and since the days began in biblical reckoning with sunset, there was some hurry necessary in the burial of Jesus. Mark 15:42 mentions this situation, and states that the next day was a sabbath. John 19:31 has reference to the exact same point, but it gives another very important truth about this upcoming sabbath -- this was not the regular sabbath but this sabbath was a high sabbath. It was not the weekly sabbath but it was the first day of the 7 day long Feast of Unleavend Bread of which the first and last days were high sabbaths, holy convocations. The beginning of this feast was always on the 15th Nisan, no matter which day of the week it might be (cp. Leviticus 23:6-8). Thus Jesus Christ died in the afternoon of the 14th Nisan and was buried the same day shortly before sunset, just before the beginning of the feast , the beginning of this high sabbath day.
All 4 Gospels do have references and mention that the grave was already empty at the beginning of the 1st day of the week (our Sunday), which means that Christ had already been risen by that time. According to his own words, he was to be buried for 3 days and 3 nights (a complete period of 3 x 24 hours according to our normal reckoning of time). Thus, we can see that he was buried late afternoon on the 14th Nisan, and he was risen from the dead late afternoon on the 17th Nisan. The records in the gospels do not mention any other events between his resurrection and the events that took place early on the first day of the week when the women came to the grave and found it to be empty. This indicates that Jesus must have been risen from the dead late Saturday afternoon, shortly before sunset which marked the beginning of the 1st day of the week.
Counting backwards now, we can easily recognize that Jesus Christ died on Wednesday, 14th Nisan, on the day before this special sabbath, the first day of the Feast of Unleavend Bread, and he was buried before sunset that day. Exactly 3 days and 3 nights later, he got up from the dead. He was 3 days and 3 nights in the heart of the earth, just as he had said. And he was also raised from the dead "on the 3rd day" still since Saturday had not yet passed.
The contradiction exists only if one takes the mentioned "sabbath" to be the regular weekly sabbath by not taking into account what John 19:31 so clearly states with ist additional information about this sabbath being a high sabbath. Such assumption puts the crucifixion and death and burial of Jesus on a Friday, which causes all the problems and makes Jesus to look like a liar. As soon as one recognizes that the sabbath was a high sabbath, the first day of the 7 day Feast of Unleavened Bread, the 15th Nisan, which could be on any day of the week according to the calendar, the problem and contradiction disappears. However, one does cleary see that the traditional teaching is in contradiction to the truth revealed in God's Word. Whom do we want to believe?