وَجَّهْتُ وَجْهِيَ لِلَّذِي فَطَرَ السَّمَاوَاتِ وَالْأَرْضَ حَنِيفًا وَمَا أَنَا مِنَ الْمُشْرِكِينَ
Wajjahtu wajhiya lillazi fataras-samawati wal-arda hanifan wa ma ana minal-mushrikin
I have turned my face toward the One who created the heavens and the earth, inclining toward truth, and I am not of those who associate others with Allah.
Another opening dua for prayer (Dua al-Istiftah)
This dua declares turning to Allah with pure monotheism.