The salat has been described in some ahadith as "the pillar of religion." Imam 'Ali (a.s.), after receiving the fatal injury by Ibn Muljim (may Allah curse him), in a part of his advice to his sons, al-Hasan and al-Husayn (a.s.) said, "[Fear] Farewell Allah, and keep Allah in view with regardst salat, for it is the pillar of your religion. [Fear] Allah, and keep Allah in the matter of the house of your Lord (i.e., mosque): do not leave it empty as long as you live."1
As-Sukuni narrates from Imam as-Sadiq (a.s.), "The Messenger of Allah (s.a.w.) said, 'Satan is frightened from a believer as long as he keeps up salat on time; but when he starts neglecting them, Satan becomes emboldened and tempts him to commit major (sins).'"2 Yazid bin Khalifa said that he heard Imam as-Sadiq (a.s.) say, "When a person stands for salat, mercy descends upon him from the heaven to the earth and the angels engulf him, and an angel calls out: 'if this person knew what is [the reward] for the salat, he would never stop.'"3
From these [few selected ahadith] we can understand the clear and obvious importance of salat in Islam. And since salat is like having audience with the Almighty Allah (as the ahadith have it that a person standing for prayer is as if he is standing in audience of the Almighty), the worshiper should approach Allah through presence of heart by not thinking or occupying his mind with anything worldly and transitory. Almighty Allah says in the Holy Qur'an:
"Indeed successful are the believers who are humble in their prayers." (24:1)
When Imam 'Ali Zaynu 'l-'Abideen (a.s.) said his salat, he used to stand "firm and motionless like a tree: nothing moves on it except what is moved by the wind."4 When the Imams, al-Baqir and as-Sadiq (a.s.), stood for their salat, "their colour would change to red and then yellow as if they were talking to someone whom they could see."5
1. The mujtahids say that salat cannot be skipped under any circumstances. It means that it is not to be omitted whether one is travelling or at home; even if the time is running out, it is obligatory upon the Muslim, for example a traveller, to say his salat in a plane, ship, car, or a train whether stationary or moving; it could be performed any where: in the waiting room, in a public park, on the side of a road, or at the work-place, etc.
2. When it is not possible for the traveller to say the salat in a plane or a car or a train in a standing position, he should say it while he is seated.
If it is not possible for him to find the direction of the qiblah, he should face the direction that he most probably thinks to be the qiblah; if he is unable to prefer one direction to the other, he should pray in whatever direction he is facing. If it is not possible to face the qiblah except for takbiratul ihram (the opening "Allahu akbar"), he should at the least say the takbir facing the direction of qiblah. (See the question-answer section below.)
3. It is permissible to ask the airhostess about the direction of the qiblah so that she may ask the pilot about it. If you have confidence in their information, you can rely on it even if they are non-Muslims.
Similarly, it is permissible to rely on scientific instruments for determining the direction of the qiblah, for example the compass, if a Muslim is convinced about its correctness.
4. If a Muslim cannot do wudhu (minor ritual ablution) for the salat, then he should do tayammum instead.
5. The length of day and night differs from place to place. If the day and the night are clearly known by the rising of the sun and its setting, the Muslim should rely on the rising and the setting of the sun for determining the times for salat and fasting. This is so even if that means that the prayers have to be said more frequently shorter days or that fasting becomes lengthier shorter nights.
6. In some places the sun does not set or does not rise at all for a number of days or months. As a matter of precaution Muslims should rely on the timings of the closest city that has night and day in a twenty-four hour period. Thus, they will, pray five salats according to the times of that closest city with the intention of qurbat in general [i.e., without saying ada (prayer on time) or qadha (prayer outside its time)].
7. If it is not possible for a Muslim to determine the beginning of true dawn (fajr) or the midday or sunset for his prayers and fasting, and he has faith in the timings given by the observatories, he can rely on the same, even if the scientists running the observatories are non-Muslims-as long as you have faith in their determining true dawn or noon or sunset times.
8. For a traveller, it is obligatory to say salat in qasr form; that is, he will recite the noon, afternoon and night prayers only two cycles (rak'at) [instead of the normal four rak'at] provided he travels for forty-four kilometers or more (in both ways), starting from the last houses of his city in normal cases.(6)
There are detailed and specific rules in the Manual of Islamic Laws explaining when to pray qasr and when not to pray qasr while travelling. (For some rules, see the questions-answers at the end of this section.)
9. Praying Friday salat with due attention to its required conditions is preferable to praying the noon salat, and is sufficient; that is, if a person says Friday prayer, he does not have to say noon prayer.
10. Praying in congregation (jama'at) is preferable to praying individually. Its preference is stronger in the dawn, sunset and night prayers. A noble hadith says: "A salat [in congregation] behind a learned scholar is like [praying] a thousand cycles; and behind a Qurayshi is like [praying] a hundred cycles." As the number of the worshippers increases, the preference [and the reward] also increases.
1. Tafsilu Wasa'ili 'sh-Shi'a, vol. 4, p. 35.
2. Imam 'Ali, Nahju 'l-Balagha (ed. Subhi as-Salih), p. 422.
3. Tafsilu Wasa'ili 'sh-Shi'a, vol. 4, p. 28.
4. Sayyid Muhammad Hadi al-Milani, Qudatuna: Kayfa Na'rifuhum, vol. 6, p. 164 which has a special section on the prayers of Imam Zaynu 'l-'Abideen (a.s.).
5. Sayyid as-Sistani, Minhaju 's-Saliheen, vol. 1, p. 193.
6. "In normal cases" means other than the major metropolitan cities where going from one end to another is considered travelling.