The Glory Be, also known as the Doxology, is one of the earliest-known prayers to refer to the Holy Trinity. In Eastern Rite Catholic churches (as well as Eastern Orthodox ones), the Sign of the Cross is made while the Glory Be is recited.
The Glory Be
"Glory be to the Father, and to the Son, and to the Holy Spirit. As it was in the beginning, is now, and ever shall be, world without end. Amen."