Some prerequisites exist regarding the offering of Prayers. These prerequisites must be fulfilled before the commencement of the Prayer, otherwise the Prayer will not be considered valid. The following are the prerequisites:
1. Knowledge that the time for the Prayer has begun:
Each prayer has its own particular time at which it must be performed. Allaah Says (what means): “…Indeed, prayer has been decreed upon the believers a decree of specified times.” [Quran 4: 103] The Prophet has clarified when the time of each prayer starts and when it ends. So anybody who prays a given prayer before its fixed time, his prayer is invalid.
2. Purity from Major and Minor impurities:
A minor impurity is one that may be removed by the performance of ablution (Wudhou’). A state of minor impurity results after defecation or urination. A major impurity requires the performance of Ghusl or ritual bathing. A state of major impurity results after sexual intercourse or sexual discharge for both men and women. Menstruation and postpartum bleeding are considered forms of major impurities. In those cases, after such conditions come to an end, women are required to make Ghusl before praying.
Allaah Almighty Says (what means): "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 Janaabah (major impurity), then purify yourselves…"[Quran 5: 6]
The Prophet said: "Allaah does not accept any prayer that was not performed while in a state of purity, nor does He accept charity from what has been stolen from booty." [Al-Bukhaari & Muslim]
3. Purity of the body, clothes and place:
Such objects should be clean of physical impurities as much as possible. If one can not remove them, he may pray with the impurities present and does not have to repeat the prayer later. Concerning bodily purity, it was related that the Prophet said: "Stay clean of urine, as the majority of punishment in the grave is due to it." [Ad-Daaraqutni]
'Ali reported: “I used to have a great deal of prostatic fluid flowing, so I asked a man to ask the Prophet about it. He asked him and the Prophet said: ‘Make ablution and wash your genital organ.’” [Al-Bukhaari]
Concerning purity of clothing, Allaah Says (what means): "And your clothing purify.” [Quran 74: 4]
Jaabir Ibn Sumrah reported that he heard a man asking the Prophet : "May I pray in the same clothes that I had on during intercourse with my wife?" He said: "Yes, but if you see some stains on it, you must wash it." [Ahmad and Ibn Maajah]
Concerning the purity of the place where one is praying, Abu Hurayrah said: "A Bedouin stood and urinated in the mosque. The people got up to grab him. The Prophet said: 'Leave him and pour a container full of water over his urine. You have been raised to be easy on the people, not to be hard on them.’" [Al-Bukhaari]
4. Covering the 'Awrah (parts of the body that should be covered)
Allaah, Almighty, Says (what means): "O children of Aadam, take your adornment at every Masjid (Mosque)…" [Quran 7: 31]
The meaning of "adornment" here is the covering of the 'Awrah. The meaning of "Mosque" is "prayer." Therefore, it means "Cover your 'Awrah for every prayer." Salamah Ibn Al-Aku' said to the Prophet : "O Messenger of Allaah, may I pray in a long shirt?" He said: "Yes, but button it, even with just a thorn." [Al-Bukhaari]
6. Facing the Qiblah:
All scholars agree that one must face the Qiblah during every prayer. Allaah Says (what means): "…Turn your face toward Al-Masjid Al-Haraam. And wherever you [believers] are, turn your faces toward it [in prayer]..." [Quran 2: 144]
If one can not determine the direction of the Qiblah, he should ask one who knows. If he finds no one to ask, he should try his best to determine it. In such a case, his prayer will be valid, and he needs not repeat it even though he discovers later on that he had faced in the wrong direction. If it is made clear to him while he is praying that he is facing the wrong direction, he needs only turn in the proper direction without stopping his prayer.
The first one is performing voluntary prayers while riding (an animal, car and so on). The rider may bend his head slightly for the bowings, but he should bend a little bit lower for the prostrations. He may face in whatever direction his ride is going.
He did not, however, do this for the obligatory prayers. Ahmad and Muslim recorded that he would pray on his mount while traveling from Makkah to Madeenah, facing away from Makkah. Upon this, Allaah revealed (what means): "…Wherever you [might] turn, there is the Face of Allaah..." [Quran 2: 115] Ibraaheem An-Nakhaa'i said: "They would pray on their mounts and animals in the direction in which they were facing." Ibn Hazm commented: "This has been related from the companions and those of the following generation, during travel and residence."
The second case is praying while having to deal with forced conditions, illness and fear. Under such circumstances, it is allowed to pray without facing the Qiblah. The Prophet said: "If I order you to do something, do what you are capable of doing." Allaah Says (what means): "And if you fear [an enemy, then pray] on foot or riding…"[Quran 2: 239]. Ibn 'Umar, may Allaah be pleased with him, added: "Facing the Qiblah or not facing it." [Al-Bukhari]
There are two cases in which one doesn't have to face the Ka'bah. 'Amr Ibn Rabee'ah reported: "I saw the Messenger of Allaah praying while riding and he faced the direction in which he was going." [Al-Bukhaari & Muslim]