Sunan Ibn Majah, Chapter: The Chapters of Establishing the Prayer and the Sunnah Regarding Them

that a man entered the mosque and performed prayer, and the Prophet (saw) was in a corner of the mosque. The man came and greeted him, and he said: "And also upon you. Go back and repeat your prayer, for you have not prayed." So he went back and repeated his prayer, then he came and greeted the Prophet (saw). He said: "And also upon you. Go back and repeat your prayer, for you have not prayed." On the third occasion, the man said: "Teach me, O Messenger of Allah!" He said: "When you stand up to offer the prayer, perform ablution properly, then stand to face the prayer direction and say Allahu Akbar. Then recite whatever you can of Quran, and then bow until you can feel at ease bowing. Then stand up until you feel at ease standing, then prostrate until you feel at ease prostrating. Then raise your head until you are sitting up straight. Do that throughout your prayer." Daif