Commentators note the similarity of thought between this verse and both Exodus 24.8 (“the blood of the covenant which the LORD has made with you”) and Zechariah 9.11 (“the blood of my covenant with you”).
This is my blood, especially in the restructuring of Good News Translation, may possibly be mistaken as a reference to the cup, but in reality it points to the wine, as one discovers in verse 29. One may then need to translate “This wine is my blood.” Both Moffatt (“this means my blood”) and Barclay (“This means my life-blood”) restructure similarly to what they did with the mention of the bread in verse 26, but for the same reason this is not a good solution to follow.
As the RSV footnote indicates, the covenant is expanded to “the new covenant” in some Greek manuscripts. However, as TC-GNT concludes, the adjective “new” was apparently brought into the text from the parallel in Luke 22.20. If it had originally been a part of the text, there is no reason why a scribe would later have dropped it.
Of the covenant is translated “which seals God’s covenant” by Good News Translation, since in the establishing of a covenant between God and his people, it was customary to use blood as a means of showing that the covenant was valid. Very often the idea of a covenant, particularly the notion of sealing or guaranteeing it, are not well known. Then translators need to express the phrase as “this is my blood that makes certain (or, establishes) the agreement God has made (with his people).”
Poured out has sometimes been rendered “shed” (for example, Barclay). Whichever expression is used, the readers must understand that it refers to death.
In the phrase for many Matthew uses a different preposition than is found in the Marcan parallel (14.24). Commentators note that Matthew’s shift is in the direction of what the Septuagint has in Isaiah 53.4, where the same preposition that Matthew employs is found in the construction “for us.” The adjective many is not restrictive in the sense of excluding some; rather it is all-inclusive, as it frequently is in the Hebrew of the Old Testament, and many translations have “all people.”
For the forgiveness of sins is not explicitly mentioned in any of the other accounts of the Lord’s Supper. Significantly enough, this phrase is not found in Matthew’s account of the preaching of John the Baptist (3.1-6), though it is included in the Marcan account (1.4). It may be necessary to provide a subject for the forgiveness of sins, as in “so that God may forgive their sins.” Bibel im heutigen Deutsch, 1st edition accurately expresses the meaning of the verse as “This is my blood, which is poured out for all people for the forgiveness of their sin. God seals his covenant with it.” Another possibility is “This is my blood, which is shed for all people so that God will forgive their sins. This blood establishes God’s agreement with his people.”
Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .