The Ruling on Mixing in Public Transport
Question :
The means of transport in our country are collective and mixed, and sometimes it happens that one touches a woman, without intending or wishing to do so, but it is the result of crowding. Are we guilty of sin in this? And what should we do, when we have no means of transport except this, and we are unable to dispense with it?
Answer:
It is incumbent upon a man to stay away from touching women and being crowded with them so that his body is in contact with their bodies, even if it be through a barrier, because it is an incentive to trial and temptation (Fitnah). A human being is not protected from sin, and he might think he is able to protect himself from this, and that he is not affected by it. But Satan reaches every part of the human body as blood reaches it, so it is possible that some impulse may emanate from him which corrupts his affairs. But if a person is compelled by absolute necessity to do this, and he takes care not to be affected by it, I hope that there will be no objection to it. But in my opinion, it is not possible to be compelled by absolute necessity to do this, since it is possible to request a place in which there is no contact with women, even if it means remaining standing; and in this way, he will escape from this problem, which causes trial and temptation (Fitnah). It is an obligation upon a man to fear Allah, Most High as much as he is able and not to be negligent in these matters.
Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 5 Pages 140-141