THE EIGHTH DAY IS THE OCTAVE OF YHVH

Tau was derived from the Phoenician letter taw  (𐤕).^[5] Letters that arose from tau include Roman T and Cyrillic Te (Т, т).
In ancient times, Sunday – which was also known as the first day of the week, was also referred to as the eighth day by Christians. This day was considered a holy day from the earliest of times by Christians (despite some weak arguments that Constantine, or the Pope, “changed the Sabbath” some 400 years later), and this was because it was the day on which Christ rose from the dead!
The resurrection of Jesus, or anastasis is the Christian belief that God raised Jesus after his crucifixion as first of the dead, starting his exalted life as Christ and Lord. In Christian theology, the death and resurrection of Jesus are the most important events, a foundation of the Christian faith and commemorated by Easter. For Christians, His resurrection is the guarantee that all the Christian dead will be resurrected at Christ's second coming. For the Christian tradition, the bodily resurrection was the restoration to life of a transformed body powered by spirit, as described by Paul and the Gospels, that led to the establishment of Christianity.

The Lord's Day in Christianity is generally Sunday, the principal day of communal worship. It is observed by most Christians as the weekly memorial of the resurrection of Jesus Christ, who is said in the canonical Gospels to have been witnessed alive from the dead early on the first day of the week. The phrase appears in Rev. 1:10. The phrase the "Lord's Day" appears only once in the Bible in Revelation 1:10 which was written near the end of the first century. It is the English translation of the Koine Greek Kyriake hemera. The adjective kyriake ("Lord's") often elided its noun, as in the neuter kyriakon for "Lord's [assembly]", the predecessor of the word "church"; the noun was to be supplied by context.

In Rev. 1:10, the apostle John, used Kyriake hemera (Κυριακῇ ἡμέρᾳ, "I was in the Spirit on the Lord's Day") in a way apparently familiar to his readers. Observers of first-day worship hold that this means he was worshiping on Sunday, resurrection day. 

Seventh-day Sabbatarians hold that since Jesus said he was "Lord of the Sabbath" and that Isaiah called the Sabbath the "Lord's Holy Day" then the Lord's Day is the Seventh-day Sabbath (i.e. Saturday). Both parties accordingly use this verse to lay claim to the name "Lord's Day" for their day of worship.

The New Testament also uses the phrase te ... mia ton sabbaton (τῇ ... μιᾷ τῶν σαββάτων, "the first day of the week") both for the early morning (Mary Magdalene John 20:1) and evening (the disciples in John 20:19) of Resurrection Sunday, as well as for the breaking of bread at Troas (Acts 20:7) and the day for the collection at Corinth (1 Co 16:2).^[4].

According to some sources, Christians held corporate worship on Sunday in the 1st century. An early example of Christians meeting together on a Sunday for the purpose of "breaking bread" and preaching is cited in the New Testament book of Acts (Acts 20:7). 2nd-century writers such as Justin Martyr attest to the widespread practice of Sunday worship (First Apology, chapter 67), and by 361 AD it had become a mandated weekly occurrence. During the Middle Ages, Sunday worship became associated w 

In the Jewish tradition, the idea of any resurrection at all first emerges clearly in the 2nd-century BC Book of Daniel, but as a belief in the resurrection of the soul alone. Josephus tells of the three main Jewish sects of the 1st century AD, that the Sadducees held that both soul and body perished at death; the Essenes that the soul was immortal but the flesh was not; and the Pharisees that the soul was immortal and that the body would be resurrected to house it.^[19][20] Of these three positions, Jesus and the early Christians appear to have been closest to that of the Pharisees. With Sabbatarian (rest) practices.The Greeks held that a meritorious man could be resurrected as a god (the process of apotheosis), 

One of the letters sent by Paul to one of the early Greek churches, the First Epistle to the Corinthians, contains one of the earliest Christian creeds referring to post-mortem appearances of Jesus, and expressing the belief that he was raised from the dead, namely 1 Corinthians 15:3–8.

[3] For I handed on to you as of first importance what I in turn had received: that Christ died for our sins in accordance with the scriptures, [4] and that he was buried, and that he was raised on the third day in accordance with the scriptures, [5] and that he appeared to Cephas, then to the twelve. [6] Then he appeared to more than five hundred brothers and sisters at one time, most of whom are still alive, though some have died. [7] Then he appeared to James, then to all the apostles. [8] Last of all, as to one untimely born,

Lorenzen finds "a strange silence about the resurrection in many pulpits". He writes that among some Christians, ministers and professors, it seems to have become "a cause for embarrassment or the topic of apologetics". According to Warnock, many Christians neglect the resurrection because of their understandable preoccupation with the Cross. he appeared also to me.