The Great Commission is the closing charge of the Gospel of Matthew, found in Matthew 28:18-20. In the King James Version it reads:
Matthew 28:18-20 (KJV)
18 And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. 19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: 20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.