What is the ruling on a marriage registrar saying: "According to the Book of Allaah and the Sunnah of the Prophet, sallallaahu alayhi wa sallam.", when writing the marriage contract?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

There is no harm for the marriage registrar to say: "According to the Book of Allaah and the Sunnah of the Prophet .", as his purpose in saying this is: "This marriage is concluded according to the Book of Allaah and the Sunnah of the Prophet ." 

Allaah Knows best.