It is narrated from Ali bin Abi Talib (may Allah be pleased with him) that when the Messenger of Allah (ﷺ) would begin the prayer, he would recite: "I have turned my face towards Him who created the heavens and the earth, and I am not among the polytheists. Indeed, my prayer, my sacrifice, my life, and my death are for Allah, the Lord of the worlds. He has no partner, and I have been commanded to do this." Muslim bin Khalid and Abdul Majeed bin Abdul Aziz—one of them said: "And I am the first of the Muslims," while the other said: "And I am among the Muslims." Imam Shafi’i (may Allah have mercy on him) said: Then he would recite the Ta’awwudh (A‘udhu billah), then recite the Qur’an, then recite Bismillah ar-Rahman ar-Raheem. When he finished (Surah Al-Fatihah), he would say "Ameen," and his followers would also say "Ameen"! If he was the Imam, he would recite aloud in the audible prayers so that his followers would also hear his voice."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 202
Hadith Takhrijأخرجہ مسلم، الصلاۃ، باب صلاۃ النبی ﷺ و دعائہ: 771۔