[Is One Obliged to Assist a Traveler Whose Car Has Broken Down?]

Answer: You are not obligated to do so as a binding duty. Rather, it falls under recommended benevolence in general, which Islam has strongly encouraged, and it carries great reward and immense recompense. It has been authentically reported that fulfilling a believer’s need is equivalent to fasting for a month and performing i‘tikaf therein. There are many reports to this effect, and the Qur’an abounds with exhortations to kindness, righteousness, and good deeds.
However, assisting the stranded person and repairing the breakdown may become obligatory in certain situations—such as when the person, his vehicle, his cargo, or his passengers are in danger. In such cases, it is not permissible to take payment or charge for the fuel used to remove the person and his car from harm. As for anything beyond that, there is no harm in charging for it.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3