“I once heard abu ‘Abd Allah (a.s.), saying that the Messenger of Allah, O Allah, grant compensation to Muhammad and his family worthy of their services to Your cause, has said, ‘In Islam al-Jalb, al-Janb and Shighar are not permissible. Shighar is one man’s giving in marriage his daughter or sister to another man to marry this man’s daughter or sister without any amount of mahr (dower) being assigned to anyone of them except that this person marries that person and the other person marries the other person.’” Al-Jalb means that a tax collector commands the tax payers to deliver what they owe to him even if he is far away. Al-Janb means in horse racing keeping of a spare horse on the side so that when one horse is exhausted the second horse can continue the race.