Wikipedia
The Words of Institution (also called the Words of Consecration) are words echoing those of Jesus himself at his Last Supper that, when consecrating bread and wine, Christian Eucharistic liturgies include in a narrative of that event. Eucharistic scholars sometimes refer to them simply as the verba (Latin for "words").
Almost all existing ancient Christian Churches explicitly include the Words of Institution in their Eucharistic celebrations, and consider them necessary for the validity of the sacrament. This is the practice of the Latin Catholic Church, the Eastern Orthodox Church, and all the churches of Oriental Orthodoxy, including the Armenian, the Coptic, the Ethiopian and the Malankara. The only ancient Mass ritual still in use that does not explicitly contain the Words of Institution is the Holy Qurbana of Addai and Mari, used for part of the year by the Assyrian and the Ancient Church of the East. The Chaldean Catholic Church and the Syro-Malabar Catholic Church, two of the Eastern Catholic Churches, use the same Anaphora, but insert in it the Words of Institution. However, the Catholic Church has explicitly recognized the validity of this Mass ritual in its original form, without explicit mention of the Words of Institution, saying that "the words of Eucharistic Institution are indeed present in the Anaphora of Addai and Mari, not in a coherent narrative way and ad litteram, but rather in a dispersed euchological way, that is, integrated in successive prayers of thanksgiving, praise and intercession."
No formula of Words of Institution in any liturgy is claimed to be an exact reproduction of words that Jesus used, presumably in the Aramaic language, at his Last Supper. The formulas generally combine words from the Gospels of Mark, Matthew and Luke and the Pauline account in . They may even insert other words, such as the phrase " Mysterium fidei", which for many centuries was found within the Roman Rite Words of Institution, until removed in 1970.