“Then he took a cup.

After giving thanks,

He gave it

To them.

He said.

‘Drink from it!

All of you!

This is my blood

Of the covenant,

Which is poured out

For many

For the forgiveness of sins.”

καὶ λαβὼν ποτήριον καὶ εὐχαριστήσας ἔδωκεν αὐτοῖς λέγων Πίετε ἐξ αὐτοῦ πάντες·

τοῦτο γάρ ἐστιν τὸ αἷμά μου τῆς διαθήκης τὸ περὶ πολλῶν ἐκχυννόμενον εἰς ἄφεσιν ἁμαρτιῶν.

This is almost word for word in Mark, chapter 14:23-24, and similar in Luke, chapter 22:17, but preceding the blessing of the bread.  John, chapter 13:53-58, has Jesus preaching about eating and drinking the body and blood of the Son of Man.  Matthew and Mark agree that Jesus took a drinking cup (καὶ λαβὼν ποτήριον), assuming this cup was filled with wine.  After giving thanks (καὶ εὐχαριστήσας), Jesus gave them this drinking cup (ἔδωκεν αὐτοῖς).  He told all of them to drink from this cup (λέγων Πίετε ἐξ αὐτοῦ πάντες).  He said that this was his blood of the covenant (τοῦτο γάρ ἐστιν τὸ αἷμά μου τῆς διαθήκης), that was to be poured out for many people (τὸ περὶ πολλῶν ἐκχυννόμενον) in order to forgive sins (εἰς ἄφεσιν ἁμαρτιῶν).  The blessing of the wine had a more elaborate narrative than the bread.  However, both would become part of the new developing Christian Eucharistic worship service.  Thus, the Greek word “εὐχαριστήσας (giving thanks)” became the name of the Last Supper Eucharist remembrance event.