1. The Messiah said that He would be three days and three nights in the heart of the earth.
2.There are those who believe in a 6th day of the week crucifixion/1st day of the week resurrection.
3. Some of those folks also believe that the "heart of the earth" is referring to the tomb.
4. However, a 6th day of the week crucifixion/first day of the week resurrection allows for only 2 night times to be involved with His time in the tomb.
5. To explain the lack of a 3rd night, some of those who believe that the 'heart of the earth' is referring to the tomb have said that the Messiah was using common figure of speech/colloquial language of the period.
6. However, to legitimately say that it was common, they would have to know of other instances where such usage was actually employed, i.e., examples where a daytime or a night time was forecast or said to be involved with an event when no part of the daytime or no part of the night time could occur.
7. Since I'm not aware of any, I'm simply curious to know what examples someone might be using in order to be able to say that the usage was common.
“For 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
Two thousand years after the fact it pays to think more like the first century authors of the New Testament than those focused on investigating matters from the vantage of a 21st century detective.
The first century scripture authors did not divide days at midnight like we do, but at sundown. In other words their day ended at sundown. According to the first century Hebrew mindset part of any day counted as a complete day of 24 hours.
That Jesus was buried on Friday evening and resurrected into new life on Sunday morning, He was in the tomb “three days and three nights” by Jewish calculating. According to our 21st century computing He was in the tomb only one full day: Saturday, the Jewish Sabbath.
Interpreting scripture must always be measured against the norms of the times when the events took place; and when they were placed on parchment while also noting the particular cultural interpretation of those events, by the witnesses who dictated their recollections to the scribes who wrote what we today call the New Testament.
In conclusion we can understand that because of the first century Jewish usage of counting any part of a day as the whole of the day, the terminology "three days and nights" is an reckoning drawn from Jewish cultural tradition of the first century.