If a person is travelling by any means of transportation which precludes his standing up for Prayer, nor can he get off from the vehicle, he can offer his Prayer while seated and the condition of facing towards the Qiblah would not be mandatory in this situation. He should face in the direction in which the mount, vehicle, boat or airplane, etc., is moving, if possible.
In the early days of Islam, the Zuhr, ‘Asr and ‘Isha’ congregational Prayer services had only two Rak‘at, just like Fajr Prayer but subsequently they continued to be of two Rak‘at length only for a person who is on a journey. In normal circumstances, the number of Rak‘at were doubled. Hence, normally, one has to perform four Rak‘at Fard each, for Zuhr, ‘Asr and ‘Isha’ Prayers while a traveller offers only two Rak‘at for each of the above-mentioned Prayers.
If a traveller reaches a place where he intends to stay less than 15 days, then this concession will apply and he will shorten his Prayers as mentioned above.
However, this concession does not apply to the Fard part of the Fajr and Maghrib Prayers.
If a person is staying with a close relative whose house he regards as his own, e.g. his parents’ home, the home of his in-laws, or a religious headquarter such as Makkah, Medina, Qadian or Rabwah, etc., he can shorten his Prayer as outlined above but it would be preferable for him to offer the full four Rak‘at as applicable.
While one is on a journey, the Sunnat part of every Prayer is dropped, with the exception of the Vitr Rak‘at in the ‘Isha’ Prayer and the two Rak‘at Sunnat of the Fajr Prayer.
To offer Nawafil during a journey, i.e. optional Prayers, are entirely up to each individual.
Moreover, it is also permissible to combine two Prayer services during a journey. Zuhr Prayer can be joined with the ‘Asr Prayer and can both be offered either at the Zuhr Prayer time or at ‘Asr Prayer time. Similarly the ‘Isha’ Prayer can be joined with the Maghrib Prayer and can be offered either at Maghrib Prayer time or ‘Isha’ Prayer time.
If travellers are offering their congregational Prayer behind an Imam who is a local inhabitant, they have to follow the Imam and offer four Rak‘at for Zuhr, ‘Asr and ‘Isha’ Prayers. The rule of concession would not apply in that case. But if the person leading the Prayer, i.e. the Imam, is a traveller, then he will shorten his Prayer accordingly and the travellers in the congregation will also finish their Prayer with the Imam, while those who are not on a journey will stand up when the Imam has recited the salutations to mark the end of Prayer and complete their Prayer.