What is the sunnah (recommended practice) that is obligatory for the traveler?

The questioner : The questioner asks: What is the sunnah (recommended practice) that is obligatory for the traveler?

The Shaykh : The word "obligatory" combined with "what is the sunnah" creates a problem for me, because if he means by sunnah the customary meaning in the time of the Messenger (peace and blessings be upon him), which includes the obligatory and the recommended, then there is an answer to that. And if he means by sunnah the voluntary acts, which is the terminology of the scholars, especially the later ones, then there is an answer to that as well. If he means the first, the sunnah that encompasses the obligatory and the recommended, then the sunnah for the traveler regarding prayer is to shorten it if it is a four-rak'ah prayer, so he prays Dhuhr, 'Asr, and 'Isha' in two rak'ahs, two rak'ahs, except if he prays behind an imam who completes the prayer, in which case it is obligatory for him to complete it, whether he catches the imam at the beginning of the prayer or catches him in the middle of the prayer, due to the generality of the saying of the Prophet (peace and blessings be upon him) , and because Ibn 'Abbas (may Allah be pleased with him and his father) was asked about a man who is with the imam and prays four rak'ahs, so he said: And based on this, we say that the sunnah for the traveler regarding shortening is to pray the four-rak'ah prayer in two rak'ahs. As for combining prayers, the sunnah is not to combine unless there is a need to be removed by it, meaning if he needs to combine, such as if he is traveling on the road and wants to stop only once, so he combines the first prayer with the second, or if he is staying and will walk, so he combines the second with the first, then it is from the sunnah to combine if that is more comfortable for him. But if there is no comfort in it for him, and the matter is the same for him, then if he wishes he combines, and if he wishes he does not combine, and not combining is better.
However, if the traveler is in a town and is one of the people of the congregation, then it is obligatory for him to attend the congregation, so he prays in the mosque with the Muslims completing the prayer and does not combine, except if he wants to travel after he prays, in which case he may combine, so he prays Dhuhr with the imam in four rak'ahs, then prays 'Asr in two rak'ahs, then walks. As for if he means by sunnah the voluntary acts, then whoever reflects on the sunnah will find that all the voluntary acts from the sunnah are done in the state of travel, except the rawatib (regular voluntary prayers) of Dhuhr, the rawatib of Maghrib, and the rawatib of 'Isha', for the sunnah is not to perform them. As for the sunnah of Fajr, the rawatib of Fajr, it is a sunnah for the traveler and the non-traveler, and likewise witr, the night prayer, the Dhuha prayer, the prayer of seeking guidance (istikharah), and other voluntary prayers, their prescribed nature for the traveler remains as it is for the resident, except for the three rawatib mentioned, which are the rawatib of Dhuhr, the rawatib of Maghrib, and the rawatib of 'Isha', for the sunnah is not to perform them.