This is My Blood which Ratifies the Agreement
Matthew 26:28 reads: “For this is my blood of the new testament” (King James). [However] the word “new” (kaines) is absent in the best and oldest manuscripts (Aleph, B, L, Z, Theta, 33, etc.) and in most modem editions (Tischendorf, Westcott and Hort, Nestle, Souter) – as well as in the parallel, Mark 14:24. It stood in the medieval text and the Latin Vulgate and passed into the translations of Wyclif, Tyndale and their successors, down to and including the King James (1611), but not into the revised versions, English or American (1881, 1901). It is usually absent from modern translations.
“The blood of the covenant” or “agreement” means, of course, the blood shed in ratifying it, as Weymouth took pains to indicate: “the blood which ratifies the Covenant.” The usual sense of the Greek idiom, “the blood of the testament” or “covenant blood,” convey nothing to the modern reader, who does not ratify his agreements with animal sacrifice. I would translate: “This is my blood which ratifies the agreement.”
– Selected from Edgar J. Goodspeed, Problems of New Testament Translation,
University of Chicago, 1945, page 40.
“I received of the Lord that which also I delivered unto you. That the Lord Jesus the same night in which he was betrayed took bread: And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: this do in remembrance of me. After the same manner also he took the cup, when he had supped, saying, This cup is the new testament in my blood: this do ye, as oft as ye drink it, in remembrance of me” (1 Corinthians 11:23-25).