Short answer
In the Hanafi school salah has six conditions before you start: purity of the body, purity of clothes and place, covering the awrah, facing the qibla, the time having begun, and intention. Inside the prayer there are six fard acts: the opening takbir, standing, recitation, ruku, the two sajdahs and the final sitting.
The conditions (shurut) are purity from hadath and najasah of body, clothes and place, covering the awrah, facing the qibla, entry of the time and intention. The pillars (arkan) are the opening takbir, standing, reciting at least one verse, ruku, two sajdahs and the final sitting for the length of the tashahhud. Missing a fard invalidates the prayer; missing a wajib by mistake is fixed with sajdah al-sahw.
Other madhhabs
- Shafi'i
- Al-Fatihah in every rakah, stillness in each position, the final tashahhud, salawat on the Prophet in it, and the first salam are all pillars.
- Maliki
- Al-Fatihah, stillness and the salam are obligatory pillars.
- Hanbali
- Al-Fatihah, stillness, the final tashahhud, salawat on the Prophet and the salam are pillars.
Explanation
Hanafi scholars divide the parts of salah into levels, and knowing the level tells you what to do when something goes wrong.
Conditions (shurut), outside the prayer:
- Purity from hadath: having wudu (ablution), and ghusl if it is needed.
- Purity of the body, clothes and place from najasah (impurity).
- Covering the awrah.
- Facing the qibla.
- The time of the prayer having begun.
- Intention (niyyah) in the heart.
Fard acts (arkan), inside the prayer:
- The opening takbir (takbirat al-ihram).
- Standing (qiyam) in fard and wajib prayers, if able.
- Reciting at least one verse of the Quran.
- Ruku (bowing).
- The two sajdahs (prostrations) in each rakah.
- The final sitting for as long as it takes to recite the tashahhud.
Wajib acts include reciting al-Fatihah, a surah after it in the first two rakats, stillness in each position, the first sitting, the tashahhud, the word "as-salam" at the end, and the qunut in witr. Missing a wajib by mistake is fixed with sajdah sahw; leaving one on purpose means repeating the prayer. Missing a fard cannot be fixed by sahw; the prayer must be prayed again.
The step-by-step method is in how to pray. For specific cases, see covering the awrah in shorts and praying in the wrong direction.
The evidence
Quran, Surah Al-Hajj 22:77
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ ٱرْكَعُوا۟ وَٱسْجُدُوا۟ وَٱعْبُدُوا۟ رَبَّكُمْ وَٱفْعَلُوا۟ ٱلْخَيْرَ لَعَلَّكُمْ تُفْلِحُونَ ۩ ﴿٧٧﴾
O you who have believed, bow and prostrate and worship your Lord and do good - that you may succeed.
Ruku and sujud are commanded.
Quran, Surah Al-Baqara 2:238
حَٰفِظُوا۟ عَلَى ٱلصَّلَوَٰتِ وَٱلصَّلَوٰةِ ٱلْوُسْطَىٰ وَقُومُوا۟ لِلَّهِ قَٰنِتِينَ ﴿٢٣٨﴾
Maintain with care the [obligatory] prayers and [in particular] the middle prayer and stand before Allah, devoutly obedient.
Standing is part of prayer.
Quran, Surah Al-Maaida 5:6
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِذَا قُمْتُمْ إِلَى ٱلصَّلَوٰةِ فَٱغْسِلُوا۟ وُجُوهَكُمْ وَأَيْدِيَكُمْ إِلَى ٱلْمَرَافِقِ وَٱمْسَحُوا۟ بِرُءُوسِكُمْ وَأَرْجُلَكُمْ إِلَى ٱلْكَعْبَيْنِ ۚ وَإِن كُنتُمْ جُنُبًۭا فَٱطَّهَّرُوا۟ ۚ وَإِن كُنتُم مَّرْضَىٰٓ أَوْ عَلَىٰ سَفَرٍ أَوْ جَآءَ أَحَدٌۭ مِّنكُم مِّنَ ٱلْغَآئِطِ أَوْ لَٰمَسْتُمُ ٱلنِّسَآءَ فَلَمْ تَجِدُوا۟ مَآءًۭ فَتَيَمَّمُوا۟ صَعِيدًۭا طَيِّبًۭا فَٱمْسَحُوا۟ بِوُجُوهِكُمْ وَأَيْدِيكُم مِّنْهُ ۚ مَا يُرِيدُ ٱللَّهُ لِيَجْعَلَ عَلَيْكُم مِّنْ حَرَجٍۢ وَلَٰكِن يُرِيدُ لِيُطَهِّرَكُمْ وَلِيُتِمَّ نِعْمَتَهُۥ عَلَيْكُمْ لَعَلَّكُمْ تَشْكُرُونَ ﴿٦﴾
O you who have believed, when you rise to [perform] prayer, wash your faces and your forearms to the elbows and wipe over your heads and wash your feet to the ankles. And if you are in a state of janabah, then purify yourselves. But if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and do not find water, then seek clean earth and wipe over your faces and hands with it. Allah does not intend to make difficulty for you, but He intends to purify you and complete His favor upon you that you may be grateful.
Wudu is a condition of prayer.
Jami' at-Tirmidhi 3
Graded hasan sahih... مفتاح الصلاة الطهور وتحريمها التكبير وتحليلها التسليم ...
"The key to prayer is purification; it begins with the takbir and ends with the salam."
Purity is a condition and the takbir opens the prayer.
Sahih al-Bukhari 757
Sahih... ارجع فصل فإنك لم تصل ...
"Go back and pray, for you have not prayed."
A prayer missing its essential parts must be repeated.
Where the ruling is recorded
- Nur al-Idah with Maraqi al-Falah, Chapters on the conditions of prayer, its pillars and its wajibat. Sets out the conditions, the pillars and the wajib acts of salah.
- al-Durr al-Mukhtar, Chapter on the description of prayer. Lists the fard and wajib acts and what each omission requires.
- Minhaj al-Talibin, Chapter on the description of prayer. The Shafi'i list of the pillars of prayer.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.