The essentials of prayer
The essentials of prayer are:
(1) Saying the opening takbeer: It is done when one commences with prayer by saying “Allahu Akbar” (Allah is the greatest) while raising the hands to shoulder level with the palms facing forward. The Prophet said: “The key to prayer is purification, its beginning is takbeer, and its end is tasleem.”[Abu Dawood and At-Tirmithi]
(2) Standing (Qiyam) after the first takbeer: One must stand during the prayer, if one is able. Allah Commands (what means): “Maintain with care the [obligatory] prayers and [in particular] the middle prayer and stand before Allah, devoutly obedient.” [Quran 2: 238], and the Prophet said: “When you stand for prayer face the Qiblah, make takbeer, utter glorification and praise Allah (Du’aa’ of Istiftah), recite the Mother of the Book (Al-Fatihah).”[Al-Bukhari] And Allah Says (what means): “So when you recite the Quran, [first] seek refuge in Allah from Satan, the expelled [from His mercy]." [Quran 16: 98]
If one can not stand, he may perform prayer sitting, lying on one's side or whatever position he is capable of taking. The Prophet said to ‘Umran Ibn Husayn : “Pray standing; if you are not able to, pray sitting; if you are not able to, pray (while lying) on your side.” [Al-Bukhari] As for the voluntary prayer, one can do it sitting even if he can stand, but one who stands receives a greater reward than one who sits. ‘Abdullah Ibn ‘Umar narrated that the Prophet said: “The prayer of one who sits is half of the prayer (of one who performs it standing).” [Al-Bukhari and Muslim]
(3) Reciting Al-Fatihah in every Rak'ah (unit) of the prayer. While standing one must properly recite the chapter of Al-Fatihah. The Prophet stated: “If anyone makes prayer and does not recite the chapter of Al-Fatihah, then his prayer is deficient and not complete...” [Muslim and Abu Dawood]
(4) Bowing: Allah Says (what means): “O you who have believed, bow and prostrate...” [Quran 22: 77] The manner of bowing is accomplished by bending over, putting one's hands on one's knees, and remaining in that position until one attains calmness.
(5) Resuming the initial standing position: In a famous narration, the Companion Abu Humayd described what the Prophet did after bowing, saying: “He would raise his head from his bowing, and then stand straight until all of his backbones returned to their places.” [Al-Bukhari and Muslim]
(6) Prostration: The Prophet explained the proper prostration by saying, “Then prostrate until you attain calmness in your prostration, then rise (and sit) until you attain calmness in your sitting, and then prostrate until you gain calmness in your prostration...” [Al-Bukhari]
(7-8) Rising in a sitting position and sitting between prostrations: Rising in a sitting position and taking a short rest in a sitting posture between the two prostrations are obligatory acts in prayer.
(9-10) The final sitting and recital of the testimonial (tashahhud): Ibn ‘Abbas said: “The Messenger of Allah used to teach us the Tashahhud like he taught us the Quran. He would say: “Attahiyyatu lillaahi was-salawaatu wat-tayyibaatu. Assalaamu alayka ayyuhan-nabiyyu wa rahmatullaahi wa barakaatuhu. Assalaamu alaynaa wa alaa ibaadillaahis-saaliheen. Ashhadu al-laa ilaaha illallaaah wa ashhadu anna Muhammadan abduhoo wa rasooluh”
(Salutations, blessings, prayers and good deeds are for Allah. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us and the sincere slaves of Allah. I bear witness that there is no god except Allah. I bear witness that Muhammad is His slave and messenger).” [Muslim and Abu Dawood]
(11) Termination (tasleem): This is when one concludes the prayer by looking to the right and left, saying “Assalamu alaykum wa rahmatullaah” (peace and Allah's mercy be upon you). ‘Amr Ibn Sa'd related that his father said: “I saw the Prophet saying the salaam on his right side and on his left side until I could see the whiteness of his cheeks.” [Muslim and Ahmad]
The majority of scholars, excepting the Hanbalis, consider uttering salaam once as sufficient.
(12) Calmness (toma’neenah): All acts and positions of prayer should be executed with calmness. Calmness is achieved by sitting in the position until the bones are set and still.
The Companion Abu Humayd said: “I am well-informed about the prayer of the Messenger of Allah and I saw him stand for prayer raising both hands to the shoulders and uttered takbeer until every bone rested in its place properly with calmness; recited the chapter of Al-Fatihah and uttered takbeer raising both hands to the shoulders; then he bowed placing his palms on his knees keeping his back straight/parallel to the floor with calmness; then stood up straight with calmness saying “Sami’allaahu liman hamidah, rabbanaa wa lakal-hamd” while raising both hands to the shoulders; then while saying takbeer, he prostrated; then he sat up onto his left foot with the right foot propped up while saying takbeer; then prostrated again while saying takbeer; then momentarily sat up again (the sitting of rest) before standing for the second unit (Rak'ah) to repeat all of the above except the opening takbeer and Duaa’ of Istiftah. In the second Rak'ah (at the point of the sitting rest), he sat more than momentarily to recite tashhahhud and prayer on the Prophet (). In the last rak'ah, he pushed his left foot forward and sat on his left hip and recited two additional supplications before concluding.” [Al-Bukhari and Abu Dawood]
(13) Sequence: Proper sequence is mandatory between the different acts of prayer. Hence the opening takbeer must come before reciting, the reciting must precede bowing, and bowing must happen before the prostration, and so on.
Undoubtedly, the fulfillment of all the necessary conditions for the prayer enhances its chances of receiving the recognition and reward of Allah. However, the satisfaction of the essentials and prerequisites of the prayer is not the only guarantee for success in this great act of worship. There are also other things a Muslim should learn such as the invalidators of prayer, its Sunnah acts, its recommended acts, etc.