It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) came into the mosque. A man entered the mosque and prayed, then he came to the Messenger of Allah (peace and blessings be upon him) and greeted him with salam. He (peace and blessings be upon him) said: "Wa 'alayka al-salam (And upon you be peace). Go back and pray again, for you have not prayed." He did this three times, and finally he said: By the One who sent you with the truth, I cannot pray better than this, so teach me the prayer. He (peace and blessings be upon him) said: "When you stand for the prayer, say 'Allahu Akbar' (Allah is the Greatest), then recite whatever of the Qur'an is easy for you, then bow with composure, then raise your head and stand up straight, then prostrate with composure, then raise your head from the prostration and sit with composure, and complete your whole prayer in this way."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2472