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. Hastening while going to the mosque or walking very quickly so as not to miss the prayers at the mosque or miss the Rukoo‘ (bowing). This makes the person lose tranquility and any respect for the prayers as well as disturb those who are praying. The Prophet said: "If the prayer is established, do not go to it while running; rather, go to it while walking with tranquility."
2. Using what causes a bad smell that people despise such as cigarettes, Hookah (sheesha) which are worse than leek, garlic or onion. Angels and people who are praying are harmed by such bad smells. Those going to attend a congregational prayer should go to the mosque with a good smell and purify themselves from these bad items.
3. 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. Many Imaams do not say the opening supplication in the prayer, or seek refuge with Allah from the devil or say the Basmalah (i.e., ‘Bismillahi Rahmanir'Raheem), or they might not say the Bismallah in the second Rak‘ah (unit) and the Rak‘ahs that follow, whereas all these matters are among the preferred acts in prayers.
5. Some late-joiners perform Takbeer while performing Rukoo‘ when they come while the Imam is performing Rukoo‘. In principle, however, Takbeerat Al-Ihram should be done while standing and then be followed by Rukoo‘. If one hastens and leaves this Takbeer for Rukoo', his prayer would nonetheless be valid and the Imam’s initial Takbeerat Al-Ihram (which he missed) will suffice him.
6. Some people raise their eyes towards the sky while praying or look to the left or right, which is what causes forgetfulness or self-whispering. People are ordered instead to lower their gaze and look at their place of prostration.
7. Some people move a lot while praying and do things such as interlocking their fingers, cleaning their nails, constantly move of the legs, adjust their headbands, look at their watch, button up, and so forth. These movements nullify the prayer or at least lessen its reward.
8. Some precede the Imam, move simultaneously with him or lag far behind him when performing prostration or Rukoo'.
9. Reading from the Mus’haf (printed Quran) during the prayer or following the recitation of the Imam by looking at the Mus’haf during the Taraweeh (Night prayers in Ramadan) Prayer and so forth without a need entails inattentiveness. If there is a need for reading from the Mus’haf, such us to correct the Imam’s recitation, there is no problem as far as necessity dictates.
10. Some curve the back or hang the head down while performing Rukoo'. It is reported that Muslims are forbidden from curving their backs, rather the back should be bent with the spine being at a right angle to the body (as far as possible) while performing Rukoo' with the head being aligned and neither raised nor lowered with respect to the head.
11. 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 do not perform Tajafi during prostration. Tajafi means keeping the abdomen away from the thighs and the shoulders away from the sides as much as possible. The praying person should not annoy the people who pray beside him and should raise his arms away from the ground and put his palms parallel to his shoulders not his knees. The person should not exaggerate in performing Tajafi by stretching his body as if he is lying on his abdomen to the extent that his head may reach the row that is ahead of him.
13. Many Imams shorten the pillars of the prayers to the extent that the people praying behind them cannot catch up with them or say the obligatory Thikr (remembrances or mentionings of Allah). This contradicts the tranquility that the Prophet asked us to apply in prayers. The Imam should keep himself in the position of Rukoo‘ or prostration for a period of time that would allow the people who are praying behind him to glorify Allah three times slowly and carefully and not quickly or hastily.
14. 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. Constant moving of the index finger or any other finger during Tashahhud. This finger should be moved only once or twice when the Shahadah (the testimony of faith) or the name of Allah is mentioned, and so forth.
16. Some move their two palms when ending the prayer towards the right and the left. The Companions, may Allah be pleased with them, would do this and the Prophet said: “Why do I see you raising your hands like the tails of the horses?” Thus, they quit doing this and turned their heads only. [Abu Dawood and An-Nasa'i]
17. 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. Many people, immediately after finishing the obligatory prayers, shake hands with the people next to them and say, “May Allah accept our and your prayer,” or, “May you get to pray at Al-Bayt Al-Haram (in Makkah)!” This is a religious innovation as it was not reported that the righteous predecessors did this.
19. Some people get up directly after ending the prayer without saying the supplications approved by the Sharee‘ah such as those glorifying Allah and praising Him and so forth. Shaykh Ibn Baz wrote a short treatise regarding the Athkar that should be said after the obligatory prayers which is very beneficial and which the reader may wish to consult.
20. 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.