A man entered the mosque while Messenger of Allah ﷺ was sitting in one side of the mosque. The man prayed, came, and greeted the Prophet. Messenger of Allah ﷺ said to him, "Wa 'Alaikas Salam (returned his greeting). Go back and pray as you have not prayed (properly)." The man returned, repeated his prayer, came back and greeted the Prophet. The Prophet ﷺ said, "Wa alaika-s-Salam (returned his greeting). Go back and pray again as you have not prayed (properly)." The man said at the second or third time, "O Messenger of Allah ﷺ! Kindly teach me how to pray". The Prophet ﷺ said, "When you stand for prayer, perform ablution properly and then face the Qibla and say Takbir (Allahu-Akbar), and then recite what you know from the Qur'an, and then bow with calmness till you feel at ease then rise from bowing, till you stand straight, and then prostrate calmly (and remain in prostration) till you feel at ease, and then raise (your head) and sit with calmness till you feel at ease and then prostrate with calmness (and remain in prostration) till you feel at ease, and then raise (your head) and sit with calmness till you feel at ease in the sitting position, and do likewise in whole of your prayer." And Abu Usama added, "Till you stand straight." (See Hadith No. 759, Vol.1)  

أَنَّ رَجُلاً دَخَلَ الْمَسْجِدَ وَرَسُولُ اللَّهِ ﷺ جَالِسٌ فِي نَاحِيَةِ الْمَسْجِدِ فَصَلَّى ثُمَّ جَاءَ فَسَلَّمَ عَلَيْهِ فَقَالَ لَهُ رَسُولُ اللَّهِ ﷺ وَعَلَيْكَ السَّلاَمُ ارْجِعْ فَصَلِّ فَإِنَّكَ لَمْ تُصَلِّ فَرَجَعَ فَصَلَّى ثُمَّ جَاءَ فَسَلَّمَ فَقَالَ وَعَلَيْكَ السَّلاَمُ فَارْجِعْ فَصَلِّ فَإِنَّكَ لَمْ تُصَلِّ فَقَالَ فِي الثَّانِيَةِ أَوْ فِي الَّتِي بَعْدَهَا عَلِّمْنِي يَا رَسُولَ اللَّهِ فَقَالَ إِذَا قُمْتَ إِلَى الصَّلاَةِ فَأَسْبِغِ الْوُضُوءَ ثُمَّ اسْتَقْبِلِ الْقِبْلَةَ فَكَبِّرْ ثُمَّ اقْرَأْ بِمَا تَيَسَّرَ مَعَكَ مِنَ الْقُرْآنِ ثُمَّ ارْكَعْ حَتَّى تَطْمَئِنَّ رَاكِعًا ثُمَّ ارْفَعْ حَتَّى تَسْتَوِيَ قَائِمًا ثُمَّ اسْجُدْ حَتَّى تَطْمَئِنَّ سَاجِدًا ثُمَّ ارْفَعْ حَتَّى تَطْمَئِنَّ جَالِسًا ثُمَّ اسْجُدْ حَتَّى تَطْمَئِنَّ سَاجِدًا ثُمَّ ارْفَعْ حَتَّى تَطْمَئِنَّ جَالِسًا ثُمَّ افْعَلْ ذَلِكَ فِي صَلاَتِكَ كُلِّهَا وَقَالَ أَبُو أُسَامَةَ فِي الأَخِيرِ حَتَّى تَسْتَوِيَ قَائِمًا  

The Prophet ﷺ said (in the above narration No. 268), "And then raise your head till you feel at ease while sitting. "  

قَالَ النَّبِيُّ ﷺ ثُمَّ ارْفَعْ حَتَّى تَطْمَئِنَّ جَالِسًا