Sorry about the length, but there is even more than what I am posting.
Jesus instituted this New Testament ordinance on the eve of His death. It was the 14th Abib/Nisan, March/April Hebrew Lunar calendar. He was our Passover, sacrificed for us and He was sacrificed on the same exact day of the year that the Passover lambs always had been slain, Exodus 12:1-6. As the Old Testament Passover commemorated Israel’s deliverance from Egypt, a type of sin, so the New Testament Lord’s Supper is a continuation of the Passover with different emblems commemorates Jesus' death, and our deliverance from sin. Immediately after the last Supper, Jesus and His disciples went out to Gethsemane, where later that night, Judas Iscariot led the bloodthirsty mob who seized Jesus, and led him away to be crucified during the morning of the 14th day of the month of Abib. Matthew 26:1-5.
The Passover is described in Exodus 12 being the 14th of the first month of the new year being Nisan (March April) according to the Jewish Lunar Solar Calendar. The Feast of Unleavened Bread is the 15th day of Nisan/April, Exodus 12:6, which begins Thursday after sundown and ends Friday at sundown. Nisan 15 being a Sabbath never changes even if current dates do not match up year after year.
Exodus 12:1-12 God gives instruction for the meal before He passes over Egypt killing the firstborn beginning at midnight. Notice they were to be fully dressed with staffs in their hands as they sat inside their dwellings and at this meal in the evening. If anything was left over from their lambs it was to be burnt up in the morning before they began their journey out of Egypt.
Hebrew weekly Sabbath starts Friday night at sunset and ends Saturday night at sunset. This was a different Sabbath called a High Sabbath not like the weekly Sabbath. This High Sabbath began the first day at sunset through the last day at sunset during the Feast of Unleavened Bread, Exodus 12:14, 15. Beginning the 14th at sunset making it Saturday the 15th to Friday the 21st at sunset. Passover is annual and not a weekly Sabbath as it is the High Sabbath that begins the first day of the Feast of Unleavened Bread and no one was to do any labor on that day as it was a day of holy assembling. Luke 23:52-54; John 19:31, 42; Leviticus 23:6-8.
Seeing that this was a High Sabbath that started at sunset on the 14th making it Saturday, the beginning day of the Feast of Unleavened Bread would have been prepared on Wednesday the 12th that Jesus ate supper with His disciples being the last supper, not the Passover Seder. On the 12th at sunset begins Thursday the 13th being the Fast of the Firstborn.
Wednesday the 12th after the disciples sat and ate with Jesus in the evening being the last supper Jesus would eat with them being in the very place in the upper room where they were told by Jesus to prepare the Passover meal. The disciples went with Him that evening, possibly after sunset making it Thursday the 13th (some call it Maundy Thursday) as He went to pray in the garden in Gethsemane.
(Note: this was not the Passover Seder, but only the last supper Jesus would eat with His disciples. Passover meal would not begin until after sunset on Friday the 14th when the 15th day begins at sunset at the end of the 14th)
Wednesday the 12th Jesus was betrayed by Judas then arrested and brought before the Sanhedrin. Thursday the 13th very early in the morning Jesus was brought before Pilate who passed sentence on Jesus and according to Roman law He was scourged and nailed to the cross about the third hour (3:00 PM) and died at the ninth hour (6:00PM) the same day when the Passover lambs were killed, Exodus 12:1-6.
Jesus was laid in the borrowed tomb on Thursday the 13th in the evening before sunset making it the 1st day and the 1st night (14th) that He died. So we have Thursday being the first day and first night – Friday 2nd day and 2nd night – Saturday 3rd day 3rd night being raised sometime between Saturday after sunset and sunrise Sunday morning.
According to Leviticus 23:5-8 The Passover feast is a different day then the Feast of Unleavened Bread as it was eaten in the evening of the 14th before the Lord passed over Egypt on the 15th.
