Matthews 28:19-20

Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. 

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Acts 2:42

And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers.