The shortest prayer most people know, said at the end of nearly everything. It asks for nothing at all. And its second half is an argument from the fourth century that you take a side in every time you say it.
It is a doxology — a word worth having — which means a short burst of praise with no request in it. Most prayers ask. This one only says who God is, in three names, and that it has always been so.
That second half is the interesting part. As it was in the beginning, is now, and ever shall be. It sounds like decoration. It is a claim: that the Son and the Spirit did not start later than the Father. In the fourth century a large part of the Church said otherwise, and this clause was written into the prayer to answer them. You have been reciting a rebuttal at the end of every psalm.
Short praises of the Father, Son and Spirit are among the oldest Christian prayers there are; they appear in the second century. The form we have was settled in the fourth, in the fight over Arius, who taught that the Son was created and so had a beginning. As it was in the beginning is the reply. By 529 a council at Vaison in Gaul was ordering it said that way in every church, on the grounds that Rome, the East and Africa already did.