Was Jesus in the tomb for 3 entire days (72 hours,) or just parts of 3 days (Friday evening, the entire Sabbath, and the morning of Sunday)? Is the Apostles Creed correct in saying, “On the third day He arose from the dead…”? This starts to drive me into all kinds of timeline questions. If it was 3 entire days, and the women found the tomb empty on the “first day of the week” i.e., Sunday, that would dictate a Wednesday crucifixion, placement in the tomb Wednesday evening, and thus a Tuesday Passover “Last Supper.” If it was “parts of 3 days,” that would allow a Thursday evening Seder, which I understand was sometimes observed (as long as it was the 19th of Nisan,) and a Friday crucifixion.
The Lord Jesus Christ said, “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” (Matt 12:40). The question is what He meant by that.
Some Evangelicals strongly believe that Jesus was in the tomb for a minimum of three full 24-hour days. They argue that He was crucified on Wednesday and went into the tomb before sundown Wednesday. In this view He was in the tomb more than 72 hours—all of Thursday, Friday, and Saturday, and parts of Wednesday and Sunday.
Others understand the expression “three days and three nights” to refer to one full day and two partial days. In that case, Jesus was crucified on a Friday (hence the expression Good Friday) and was placed in the tomb before sundown on Friday—day 1. He was in the tomb all of Saturday—day 2. He was in the tomb for parts of Sunday (circa 6PMi to 6AM) before He rose on Sunday morning—day 3.
Believer’s Study Bible says, “The phrase ‘three days and three nights’ does not necessarily denote a 72-hour period. In Hebrew thought, a part can constitute the whole in time reckoning. Thus Jonah was in the belly of the great fish at least part of three separate days” (s.v., Jonah 1:17).ii
Others suggest that He was crucified and buried on Thursday and that it was three days between Thursday and Sunday based on the way we think of time. (If you are with someone Thursday afternoon and will have breakfast with them on Sunday morning, you might well say, “I’ll see you in three days,” even though it is only about 66, not 72, hours away, and even though parts of four days—Thursday, Friday, Saturday, and Sunday—are included).
Still others suggest that three days and three nights simply proved that He was dead. In his commentary on Jonah 1:17, Stuart says,
Three days and three nights is a special phrase used in the ancient world with the meaning ‘long enough to be definitely dead’. It derives originally from the ancient pagan notion that the soul’s trip to the after-world took three days and nights. Jesus’ use of the same phrase for the duration of his death before his resurrection (Mt. 12:40) carries a similar force: it is a way of saying that he would really die, not that he would be literally dead for exactly seventy-two hours (“Jonah” in New Bible Commentary, p. 819).iii
The OT counted as a whole year, parts of any year, during which a king in Judah reigned. This was the ascension-year system (see here). So, there were overlapping reigns, when one king reigned part of that year and another king began his reign that same year. The same was true with counting days. Even a part of a day was counted as a day.
I am convinced that the Lord Jesus was crucified from 9AM to 3PM (Mark 15:24-25) and buried before sundown on Friday. However, I do not see this as a fundamental issue. That He died for our sins is a fundamental issue. When He died for our sins is not.
Except for replacing the word believe with trust, this statement by GotQuestions.org (see here) is excellent IMO:
In the grand scheme of things, it is not all that important to know what day of the week Christ was crucified. If it were very important, then God’s Word would have clearly communicated the day and timeframe. What is important is that He did die and that He physically, bodily rose from the dead. What is equally important is the reason He died—to take the punishment that all sinners deserve. John 3:16 and 3:36 both proclaim that putting your trust in Him results in eternal life! This is equally true whether He was crucified on a Wednesday, Thursday, or Friday.
i We start a new day at midnight. They started a new day at sundown, or around what we call 6PM.
ii See also Jamieson, Fausset, and Brown: “probably, like the Antitype, Christ, Jonah was cast forth on the land on the third day (Mt 12:40); the Hebrew counting the first and third parts of days as whole twenty-four hour days” (Commentary Critical and Explanatory on the Whole Bible, vol. 1, p. 684).
iii See also Clendenen, “The Minor Prophets” in Holman Concise Bible Commentary (p. 362): “The ‘three days and three nights’ of 1:17 alluded to the notion popular at that time that the journey to the land of the dead (sheol) took that long. So Jonah’s retrieval from the fish was like a retrieval from death (Matt. 12:39–40).”