Dr. Luther’s Small Catechism lesson for the week of January 11, 2015:
[IV] THE SACRAMENT OF HOLY BAPTISM
IN THE PLAIN FORM IN WHICH THE HEAD OF THE FAMILY
SHALL TEACH IT TO HIS HOUSEHOLD
What is baptism?
Answer: Baptism is not merely water, but it is water used according to God’s command and connected with God’s Word.
What is this Word of God?
Answer: As recorded in Matthew 28:19, our Lord Christ said, “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit.” 
 Tappert, T. G. (Ed.). (1959). The Book of Concord The Confessions of the Evangelical Lutheran Church. (p. 348). Philadelphia: Mühlenberg Press.