Absolutely Necessary Condition for Travelling with a Mahram

Mas-alah: It is only permissible for a mahram to go along on safar when there is no fear of fitnah and shahwat. [In other words, there should be no fear of the two becoming embroiled in any sexual misdemeanour or even their sexual feelings becoming aroused.]

If there is a strong feeling that when travelling and being alone or when some unavoidable physical contact occurs, lust will be aroused, then it is not permissible for the two to travel together. (Mu’allimul Hujjaaj)

(Mukammal Wa Mudallal Masaail-e-Haj Baraae Khawaateen)