Luther refers to this quote from Cyprian (AE 45:41). The value of children, just on the basis of the First Article, is here beautifully expressed. To kiss an infant is to kiss the Hands of God:
In the kiss of an infant, each of us should, for very piety, think of the recent Hands of God, which we in a manner kiss, in the lately formed and recently born man, when we embrace that which God has made.
The Epistles of St. Cyprian (“A Library of Fathers of the Holy Catholic Church Anterior to the Division of the East and West” [Oxford: Parker, 1844]), p. 197.