Summary of answer:
Praise be to Allah
With regard to a traveller who commits sins whilst travelling, one of two scenarios must apply:
The first scenario:
is where the main purpose of his trip is to commit forbidden acts, such as one who travels for the purpose of doing immoral deeds, drinking alcohol, fighting the Muslims and so on. In such cases it is not permissible to help him with his travel in any way whatsoever, and the fuqaha’ describe him as “one who sins by travelling”.
The majority of scholars are of the view that the concessions of travel are not allowed in his case, because this would be helping him to commit sin.
Al-Ghazaali said: With regard to the one who sins by travelling, no concessions are granted to him, as is also the case with regard to runaway slaves, those who travel in defiance of their parents, and bandits, because the concession is a kind of help, and no one is to be helped in sin.
End quote from al-Waseet fi’l-Madhhab (2/251)
The concessions in travel are affirmed to help with what the traveller suffers of hardship and difficulty, and it is far-fetched to suggest that the Lawgiver would prescribe anything that would help in sin.
End quote from Nihaayat al-Matlab fi Diraayat al-Madhhab (2/459).
Shaykh al-Islam said:
If he is sinning by undertaking this journey, as in the case of bandits and the like, is it permissible for him to avail himself of the concessions of travelling, such as breaking the fast and shortening the prayer? There is a difference of opinion concerning that.
The view of Maalik, ash-Shaafa‘i and Ahmad is that it is not permissible for him to shorten his prayers and break the fast. The view of Abu Haneefah is that it is permissible for him to do that.
End quote from Majmoo‘ al-Fataawa (18/254)
The second scenario:
is where the main purpose of his trip is something permissible, but he may commit sins whilst travelling. In this case there is nothing wrong with helping him with travelling, and this is not regarded as coming under the heading of helping in sin, because the help in this case is with permissible travel, not with the sin that he may commit during his journey.
The fuqaha’ call this “one who sins whilst travelling”.
The fuqaha’ have said that the one who sins whilst travelling may avail himself of the concessions of travel, which means that this does not come under the heading of helping in sin.
As for the one who sins whilst travelling, this is a person whose journey is permissible, but on the way he commits some sin like drinking alcohol and so on. It is permissible for him to avail himself of the concessions.
End quote from al-Usool wa’d-Dawaabit (p. 44)
Ibn Taymiyah said:
Hence the fuqaha’ spoke of the diffeence between the one who sins by travelling and the one who sins whilst travelling. They said: If he undertakes a permissible journey, such as Hajj, ‘umrah or jihad, it is permissible for him to shorten his prayers and break his fast, according to the consensus of the four imams, even if he commits sin during that journey.
End quote from Majmoo‘ al-Fataawa (18/254).
The concession is prescribed so as to make things easier and help with travel, and there is no way that help should be given to the sinner in committing sin. This is in contrast to cases where the journey is permissible, but he commits sins en route. He should not be prevented from travelling; rather he should be prevented from committing sin.
End quote from al-‘Azeez Sharh al-Wajeez (2/223)
If he is not to be prevented from travelling – as ar-Raafi‘i said – then he is not to be prevented from availing himself of the means thereof either.
Shaykh Ibn ‘Uthaymeen said:
The difference between them is that in the first case, his only motive for travelling is to commit sin. In the second case, he has a different aim in mind, but he commits sin whilst travelling.
A similar case is if someone rents a building from you from you, for the purpose of setting up a stage in it for entertainment. Renting it to him is haraam. But if he rents it from you in order to live in it, then he sets up a stage in it for entertainment, then renting it to him is not haraam. The difference is that in the first case he rented it in order to do something that is prohibited, but in the second case he rented it in order to do something that is permissible, but then he did something prohibited in it.
End quote from Ta‘leeqaat Ibn ‘Uthaymeen ‘ala al-Kaafi (3/126)
If Islam grants the concessions of travel to a sinner when he is travelling, which help him with his journey, then that also applies to other matters that have to do with his journey, such as booking airline travel, hotels and so on.
We asked our shaykh, ‘Abd ar-Rahmaan al-Barraak (may Allah preserve him) about this issue, and he said: If the purpose of the trip is permissible, but the traveller may commit some forbidden acts, then there is nothing wrong with making bookings for him. But if the journey is for a forbidden purpose, then it is not permissible to help him with it. End quote.