It is well known to every Muslim that sincerity to Allah and compliance with the Sunnah of the Prophet are the two conditions for the acceptance of deeds and that any deed that does not meet these two conditions is rejected. The Prophet said: "Whoever does something that does not belong to our matter (religion), it will be rejected." [Muslim]
Because of the importance of prayers and its great position in Islam and the fact that many people take them lightly and violate many of their rulings it was necessary to highlight important points regarding the mistakes that are made by some people while they are praying. Additionally, it is equally important to clarify the positions of the Imam with respect to the people who are praying behind him in congregational prayer.
These clarifications and highlights are vital in order that prayer is performed in a perfect way that frees one's liability and makes one gain its full reward, because many people violate the instructions regarding the manner in which to perform the prayers. The following are some such matters: [Al-Bukhari and Muslim]
1. Not raising the hands at the Takbeerat Al-Ihram (the initial ‘Allahu Akbar’) or at performing Rukoo‘ or after rising from Rukoo' and after standing up after performing the first Tashahhud (the first supplication said when sitting), which are all from the acts of Sunnah (recommendation) in prayers. Also, raising the hands when performing Takbeer at the Funeral Prayer, the ‘Eed and the Istisqaa’ (rain-seeking) prayers.
4. Some precede the Imam, move simultaneously with him or lag far behind him when performing prostration or Rukoo'.
9. Some do not perform prostration perfectly by prostrating on the trim of the turban and without placing the forehead on the ground, or they place the forehead on the ground but raise the nose or the feet from the ground. One who does so does not prostrate on the seven organs that are required for perfecting the prostration as mentioned in the Hadeeth of the Prophet .
12. Some perform the Tawarruk (a seated position where the left leg is under the right shin) in the two-Rak‘ah prayers such as the Fajr, the Friday or the voluntary prayers, while not performing it in the four-Rak‘ah or three-Rak‘ah prayers during the last Tashahhud. It is permissible to either perform Tawarruk or not to perform it, but it is better to apply the Sunnah of the Prophet . The Sunnah is to perform Tawarruk during the last Tashahhud of the three-Rak‘ah or four-Rak‘ah prayer provided that the person will not annoy those who are beside him.
15. Many people do not wear clothing that covers the body properly, but instead wear insufficient trousers and shirts such that when they perform Rukoo‘, the shirt moves and part of their back and buttocks get exposed and people who pray behind them see it. The exposure of any part of the ‘Awrah (part of the body that must be covered according to Islam) nullifies the prayer.
18. Some people raise their hands and start supplicating to Allah after ending the prayer directly and thus do not say the Athkar that are approved by the Sharee‘ah, and this contradicts the Sunnah of the Prophet . Supplication should be said after finishing the Athkar as this makes the supplication worthier of acceptance. Supplication after voluntary prayers also is worthier of acceptance than others.