Firstly: The Definition of a Wayfarer
Ibn al-Sabil linguistically: is the traveller. Sabil means way. The traveller is referred to as the 'son of the way' due to his traversing it. The adherent to a thing may be nicknamed its son. It is said to a person always going out at night walad al-layl – literally, the son of night, and ibn al-ma' is the bird who lives around water.
Ibn al-Sabil technically: is the estranged who has no way to return to his land, even if he is wealthy there.
Secondly: The Wayfarer as an Avenue of Expenditure for Charity
The wayfarer is one of the eight valid avenues of expenditure of legal charity. Consensus has been quoted on this by: Ibn al-Mundhir, Ibn Hazm, and Ibn Qudamah.
Thirdly: The Wayfarer's Share to One Who Travels for Sin
Legal charity is not given to one who was travelling for a sinful cause, unless he repents. This has been explicitly mentioned by the majority: Malikis, Shafi`is, Hanbalis, and Zahiris.
Fourthly: Inability to Borrow as a Condition for the Wayfarer's Charity
It is not necessary for the wayfarer to borrow, even if he finds one who will lend him money. This is the position of the majority: Hanafis, Shafi`is, Hanbalis, and a position among Malikis.
Fifthly: The Share of the Wayfarer to One Intending Travel
The share of the wayfarer is not given to he who wishes to commence a travel from his land. This is the position of the majority: Hanafis, Malikis, and Hanbalis
Sixthly: The Amount the Wayfarer Receives
The wayfarer receives enough to allow him to return to his land, and this is by agreement of the four schools of jurisprudence.