The Gospels of Mark and Matthew allude to the ceremony in which the Israelites make a covenant to keep the Law given by God (the Decalogue and the rest of the law given in Exodus; Ex. 20-23). The ceremony takes place in Ex. 24:4-8 and is a sacrifice in which Moses splatters the blood of the sacrifice either on the people or on pillars representing the people: “Moses took the blood and dashed it on the people and said, ‘See the blood of the covenant that the Lord has made with you in accordance with all these words'” (Ex. 24:8).
In Matt. 26:27-28 (NET), Jesus says, after giving his disciples the cup: ““Drink from it, all of you, for this is my blood, the blood of the covenant, that is poured out for many for the forgiveness of sins.” (or “for this is my blood of the covenant that is poured out for many.”)
The Greek looks like this (using Blue Letter Bible):
Jesus adds “my” (μου) which modifies blood (“αἷμά”), but otherwise the passages are identical. Some witnesses add “new” to modify covenant (“διαθήκης”), although it’s not clear if that’s a late addition or not (see NET Matt 26:27, footnotes 37 and 38).
I think this is a fascinating use and reworking of the covenant between God and the children of Israel mediated by Moses. It’s especially interesting that Jesus (and/or Matthew) sidesteps the Passover context that the synoptic gospels place Jesus’ death in favor of the covenant between Israel and God at Sinai. Jesus is making a new covenant and he does so by reworking some of the language of a previous covenant.