Ali bin Yahya bin Khallad bin Rafi' narrates from his father, and he from his uncle Rifa'ah bin Rafi' (may Allah be pleased with him), that the Prophet (peace and blessings be upon him) said: "When you stand for your prayer, say 'Allahu Akbar' (Allah is the Greatest), then recite whatever you know of the Qur'an." It also contains: "When you sit in the middle of the prayer, sit calmly and lay your left thigh flat, then recite the tashahhud; then when you stand (for the third rak'ah), do the same, until you finish your prayer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2798